ANTI-SKID BRAKING SYSTEM (ABS) <4WD> Click on the applicable bookmark to selected the required model year 35B-1 ANTI-SKID BRAKING SYSTEM (ABS) <4WD> CONTENTS Click on the applicable bookmark to selected the required model year GENERAL INFORMATION . . . . . . . . . . . . . . . . . . 3 Brake Fluid Level Sensor Check . . . . . . . . . . . . . . . . . . . . . . . . . . Refer to GROUP 35A SERVICE SPECIFICATIONS . . . . . . . . . . . . . . . . . 3 Bleeding . . . . . . . . . . . . . . . . . Refer to GROUP 35A LUBRICANTS . . . . . . . . . . Refer to GROUP 35A Disc Brake Pad Check and Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . Refer to GROUP 35A SEALANTS . . . . . . . . . . . . Refer to GROUP 35A Disc Brake Rotor Check . . . Refer to GROUP 35A SPECIAL TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Brake Disc Thickness Check . . . . . . . . . . . . . . . . . . . . . . . . . . Refer to GROUP 35A TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . 5 Brake Disc Run-out Check and Correction . . . . . . . . . . . . . . . . . . . . . . . . . . Refer to GROUP 35A ON-VEHICLE SERVICE . . . . . . . . . . . . . . . . . . . . 22 Wheel Speed Sensor Output Voltage Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Brake Pedal Check and Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . Refer to GROUP 35A ABS Warning Lamp Relay Continuity Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Brake Booster Operating Test . . . . . . . . . . . . . . . . . . . . . . . . . . Refer to GROUP 35A Hydraulic Unit Check . . . . . . . . . . . . . . . . . . . . . . . . 24 Check Valve Operation Check . . . . . . . . . . . . . . . . . . . . . . . . . . Refer to GROUP 35A Load Sensing Spring Length Check and Adjustment . . . . . . . . . . . . . . . Refer to GROUP 35A Load Sensing Proportioning Valve Function Test . . . . . . . . . . . . . . . . . . . . . Refer to GROUP 35A Remedy for a Flat Battery . . . . . . . . . . . . . . . . . . . 25 BRAKE PEDAL . . . . . . . . Refer to GROUP 35A MASTER CYLINDER AND BRAKE BOOSTER . . . . . . . . . . . . Refer to GROUP 35A CONTINUED ON NEXT PAGE 35B-2 FRONT DISC BRAKE . . Refer to GROUP 35A HYDRAULIC UNIT AND ABS-ECU . . . . . . . . . 26 REAR DISC BRAKE . . . . Refer to GROUP 35A WHEEL SPEED SENSOR . . . . . . . . . . . . . . . . . . 29 LOAD SENSING PROPORTIONING VALVE . . . . . . . . . . . . . . . . . Refer to GROUP 35A G SENSOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 ABS <4WD> – General Information/Service Specifications 35B-3 GENERAL INFORMATION The ABS consists of components such as the wheel speed sensors, stop lamp switch, hydraulic unit assembly (integrated with the ABS-ECU) and the ABS warning lamp. If a problem occurs in the system, the malfunctioning components can be identified and the trouble symptoms will be memorized by the diagnosis function. In addition, reading of diagnosis codes and service data and actuator testing are possible by using the MUT-II. WHEEL SPEED SENSOR Type Magnet coil type ABS rotor teeth 43 CONSTRUCTION DIAGRAM ABS warning lamp Hydraulic unit assembly (integrated with the ABS-ECU) Diagnosis connector G-sensor Wheel speed sensor Stop lamp switch Wheel speed sensor SERVICE SPECIFICATIONS Items Standard value Wheel speed sensor internal resistance kΩ 1.30 – 1.58 Wheel speed sensor insulation resistance kΩ 100 or more G sensor output voltage V When labeled surface is faced to vertical direction 2.4 – 2.6 When labeled surface is faced straight down 3.3 – 3.7 35B-4 ABS <4WD> – Special Tools SPECIAL TOOLS Tool Number Name Use MB991502 MUT-II sub assembly For checking of ABS (Diagnosis code display when using the MUT-II) MB991529 Diagnosis code check harness For checking of ABS (Diagnosis code display when using the ABS warning lamp) MB991547 ABS check harness For measuring of ABS-ECU terminal voltage MB991348 Test harness set For checking of G sensor ABS <4WD> – Troubleshooting 35B-5 TROUBLESHOOTING STANDARD FLOW OF DIAGNOSTIC TROUBLESHOOTING Refer to GROUP 00 – How to Use Troubleshooting/Inspection Service Points. NOTES WITH REGARD TO DIAGNOSIS 1. The phenomena listed in the following table are not abnormal. Phenomenon Explanation of phenomenon System check sound When starting the engine, a thudding sound can sometimes be heard coming from inside the engine compartment, but this is because the system operation check is being performed, and is not an abnormality. ABS operation sound 1. 2. 3. System check sound When depressing the brake pedal during driving, a shock is sometime felt. Sound of the motor inside the ABS hydraulic unit operation. (whine) Sound is the generated along with vibration of the brake pedal. (scraping) When ABS operates, sound is generated from the vehicle chassis due to repeated brake application and release. (Thump: suspension; squeak: tyres) 2. For road surfaces such as snow-covered roads and gravel roads, the braking distance for vehicles with ABS can sometimes be longer than that for other vehicles. Accordingly, advise the customer to drive safely on such roads by lowering the vehicle speed and not being too overconfident. 3. Diagnosis detection condition can vary depending on the diagnosis code. Make sure that checking requirements listed in the “Comment” are satisfied when checking the trouble symptom again. Caution Use the special tool (MB991547) when checking the terminal voltage and resistance of ABS-ECU. 35B-6 ABS <4WD> – Troubleshooting ABS WARNING LAMP INSPECTION Check that the ABS warning lamp illuminates as follows. 1. When the ignition key is turned to “ON”, the ABS warning lamp illuminates for approximately 3 seconds and then switches off. 2. When the ignition key is turned to “START”, the ABS warning lamp remains illuminated. 3. When the ignition key is turned from “START” back to “ON”, the ABS warning lamp illuminates for approximately 3 seconds and then switches off. ABS warning lamp Approx. 3 s ABS warn- Illuminated Not illumiing lamp nated START Ignition ON switch ACC, LOCK Approx. 3 s NOTE The ABS warning lamp may remain on until the vehicle reaches a speed of several km/h. This is limited to cases where diagnosis code Nos.21 to 24, 53 or 55 have been recorded because of a previous problem occurring. In this case, the ABS-ECU keeps the warning lamp illuminated until the problem corresponding to that diagnosis code can be detected. 4. If the illumination is other than the above, check the diagnosis codes. DIAGNOSIS FUNCTION READING DIAGNOSIS CODES Read a diagnosis code by the MUT-II or ABS warning lamp. (Refer to GROUP 00 – How to Use Troubleshooting/Inspection Service Points.) NOTE Connect the MUT-II to the diagnosis connector (16-pin). ERASING DIAGNOSIS CODES When using the MUT-II Connect the MUT-II to the diagnosis connector (16-pin) and erase the diagnosis code. Caution Turn the ignition key to the LOCK (OFF) position before connecting or disconnecting the MUT-II. 35B-7 ABS <4WD> – Troubleshooting When not using the MUT-II 1. Stop the engine. 2. Use the special tool to earth terminal (1) (diagnosis control terminal) of the diagnosis connector. 3. Turn on the stop lamp switch. (Depress the brake pedal.) 4. After carrying out steps 1. to 3., turn the ignition switch to ON. Within 3 seconds after turning the ignition switch to ON, turn off the stop lamp switch (release the brake pedal). Then, turn the stop lamp switch on and off a total of 10 times. MB991529 NOTE If the ABS-ECU function has been stopped because of fail-safe operation, it will not be possible to erase the diagnosis codes. ON Ignition switch LOCK (OFF) Stop lamp switch ON OFF 1 second ABS warning lamp ON OFF ABS-ECU memory Within 3 seconds Within 1 second 1st Within 1 second Within Within 1 1 second second Within Within Within Within 1 1 1 1 second second second second Within Within 1 1 second second 2nd 3rd 4th 5th 6th 7th 8th 9th 10th Erasing of ABS-ECU diagnosis codes complete. 35B-8 ABS <4WD> – Troubleshooting INSPECTION CHART FOR DIAGNOSIS CODES Diagnosis code No. Inspection item Reference page 11 Front right wheel speed sensor (Open circuit or short circuit) 35B-9 12 Front left wheel speed sensor (Open circuit or short circuit) 35B-9 13 Rear right wheel speed sensor (Open circuit or short circuit) 35B-9 14 Rear left wheel speed sensor (Open circuit or short circuit) 35B-9 15 Wheel speed sensor (Abnormal output signal) 35B-10 16* ABS-ECU power supply system (Abnormal voltage drop or rise) 35B-11 21 Front right wheel speed sensor 35B-9 22 Front left wheel speed sensor 35B-9 23 Rear right wheel speed sensor 35B-9 24 Rear left wheel speed sensor 35B-9 32 G sensor system 35B-12 33 Stop lamp switch system 35B-13 41 Front right solenoid valve 42 Front left solenoid valve 43 Rear right solenoid valve 44 Rear left solenoid valve 51 Valve relay problem (stays on) 35B-26, 27 (Replace the hydraulic unit and ABS-ECU.) 52 Valve relay problem (stays off) or ABS-ECU power supply system problem 35B-13 53 Motor relay problem (stays off) or ABS-ECU power supply system problem 54 Motor relay problem (stays on) 35B-26, 27 (Replace the hydraulic unit and ABS-ECU.) 55 Motor system (seized pump motor) or ABS-ECU power supply system problem 35B-13 63 ABS-ECU 35B-26, 27 (Replace the hydraulic unit and ABS-ECU.) The diagnosis codes are output when there is no response to the drive signals for respective solenoid ECU power valves or the ABS ABS-ECU supply system is defective. NOTE *: Turning the ignition switch to ACC will erase the diagnosis code No.16. 35B-13 35B-9 ABS <4WD> – Troubleshooting INSPECTION PROCEDURE FOR DIAGNOSIS CODES Code Nos.11, 12, 13 and 14 Wheel speed sensor (open circuit or short circuit) Probable cause Code Nos.21, 22, 23 and 24 Wheel speed sensor Code Nos. 11, 12, 13 and 14 are output if the ABS-ECU detects an open circuit or short-circuit in the (+) wire or (–) wire in any one of the four wheel speed sensors. D Malfunction of wheel speed sensor D Malfunction of wiring harness or connector D Malfunction of hydraulic unit and ABS-ECU Code Nos. 21, 22, 23 and 24 are output in the following cases. D When there is no input from any one of the four wheel speed sensors when travelling at several km/h or more, even though open circuit can not be verified. D When a chipped or blocked-up ABS rotor is detected and if the anti-lock system operates continuously because a malfunctioning sensor or a warped ABS rotor is causing sensor output to drop. D D D D D D NG Wheel speed sensor installation check OK NG Measure at the ABS-ECU connector A-58. D Disconnect the connector, and measure at the harness side connector. D Resistances between 17 and 18, 15 and 14, 2 and 1, 4 and 5 OK: 1.30 – 1.58 kΩ OK Wheel bearing check (Refer to GROUP 26 and GROUP 27 – On-vehicle Service.) Check the following connector: A-58 OK Check the trouble symptom. NG Replace the hydraulic unit and ABS-ECU. NG Repair Replace Check the trouble symptom. NG Repair NG NG ABS rotor check (Refer to P.35B-30.) OK NG Check the following connectors: A-58, C-25<L.H. drive vehicles>, C-24<R.H. drive vehicles>, A-24, A-85, D-24, D-28 NG Wheel speed sensor check (Refer to P.35B-30.) OK Wheel speed sensor check (Refer to P.35B-30.) Replace Wheel speed sensor output voltage check (Refer to P.35B-22.) NG Repair OK OK OK Malfunction of wheel speed sensor Malfunction of wiring harness or connector Malfunction of ABS rotor Too much gap between the sensor and the ABS rotor Malfunction of hydraulic unit and ABS-ECU Malfunction of wheel bearing Replace Check the harness wire, and repair if necessary. D Between each wheel speed sensor and ABS-ECU 35B-10 ABS <4WD> – Troubleshooting Code No.15 Wheel speed sensor (Abnormal output signal) Probable cause This code is output if the output signal of any wheel speed sensor is abnormal (other than an open circuit or short circuit). D D D D D D D NO Are four tyres equal in size? Unequal tyre size Improper installation of wheel speed sensor Malfunction of wheel speed sensor Malfunction of wiring harness or connector Malfunction of ABS rotor Malfunction of wheel bearing Malfunction of hydraulic unit and ABS-ECU Equalize sizes on all tyres. YES Check the trouble symptom. NG Check the wheel speed sensor installation condition. NG Repair OK Check the wheel speed sensor output voltage. (Refer to P.35B-22.) NG Check the wheel speed sensor. (Refer to P.35B-30.) OK OK Replace Check the following connector: A-58 OK Check the trouble symptom. NG NG Repair Check the ABS rotor. (Refer to P.35B-30.) OK NG Replace NG Replace the hydraulic unit and ABS-ECU. Check the wheel bearing. (Refer to GROUP 26 and GROUP 27 – On-vehicle Service.) OK Check the trouble symptom. NG Replace NG Check the harness wire, and repair if necessary. D Between each wheel speed sensor and ABS-ECU 35B-11 ABS <4WD> – Troubleshooting Code No.16 ABS-ECU power supply system (abnormal voltage drop or rise) Probable cause This code is output if the ABS-ECU power supply voltage drops below or rises above the rated values. Furthermore, turning the ignition switch to ACC will erase this code. D Malfunction of battery D Malfunction of wiring harness or connector D Malfunction of hydraulic unit and ABS-ECU Caution If battery voltage drops or rises during inspection, this code will be output as well. If the voltage returns to standard value, this code is no longer output. Before carrying out the following inspection, check the battery level, and refill it if necessary. NG Measure at the ABS-ECU connector A-58. D Disconnect the connector, and measure at the harness side connector. D Start the engine. Voltage between 10 and body earth OK: System voltage Check the following connectors: A-58, C-40 <R.H. drive vehicles>, C-02 <R.H. drive vehicles>, C-78 <L.H. drive vehicles>, C-76 <R.H. drive vehicles>, C-74 OK NG OK Check the trouble symptom. Check the following connector: A-58 OK Check the trouble symptom. NG Replace the hydraulic unit and ABS-ECU. NG Repair NG Repair Check the harness wire, and repair if necessary. D Between ignition switch and ABS-ECU 35B-12 ABS <4WD> – Troubleshooting Code No.32 G sensor system Probable cause This code is output in the following cases. D G sensor output voltage is less than 0.5 V or more than 4.5 V. (An open or short circuit is present in the G sensor circuit.) D G sensor output voltage does not change. (G sensor output voltage is abnormal.) D Malfunction of G sensor D Malfunction of wiring harness or connector D Malfunction of hydraulic unit and ABS-ECU NG G sensor check (Refer to P.35B-31.) Replace OK Measure at the G sensor connector D-29. D Disconnect the connector, and measure at the harness side connector. D Ignition switch: ON D Voltage between 1 and body earth OK: System voltage NG Check the following connector: D-29 OK Check the trouble symptom. NG Repair NG OK Check the harness wire, and repair if necessary. D Between ignition switch and G sensor Measure at the ABS-ECU connector A-58. D Disconnect the connector, and measure at the harness side connector. D Ignition switch: ON D Voltage between 7 and 20 OK: 2.4 – 2.6 V (When labeled surface is faced to vertical direction) Check the following connectors: A-58, C-25 <L.H. drive vehicles>, D-29 OK Check the trouble symptom. NG Repair NG OK Check the following connector: A-58 OK Check the trouble symptom. NG NG Repair NG Replace the hydraulic unit and ABS-ECU. Check the harness wire, and repair if necessary. D Between G sensor and ABS-ECU 35B-13 ABS <4WD> – Troubleshooting Code No.33 Stop lamp switch system Probable cause This code is output in the following cases. D If the stop lamp switch is continuously on for 15 minutes or more even though the ABS system is not operating. D If there is an open circuit in the stop lamp switch input circuit harness. D Malfunction of stop lamp switch D Malfunction of wiring harness or connector D Malfunction of hydraulic unit and ABS-ECU NO Does the stop lamp turn on and off normally? Check the stop lamp switch installation condition. (Refer to GROUP 35A – On-vehicle Service.) YES OK Measure at the ABS-ECU connector A-58. D Disconnect the connector, and measure at the harness side connector. D Stop lamp switch: ON D Voltage between 3 and body earth OK: System voltage OK Repair Check the stop lamp switch. (Refer to GROUP 35A – Brake Pedal.) OK NG NG Check the following connector: A-58 OK NG Replace Check the following connectors: A-58, C-28 <L.H. drive vehicles>, C-41 <R.H. drive vehicles> NG Repair OK Check the trouble symptom. Check the following connectors: C-28 <L.H. drive vehicles>, C-41 <R.H. drive vehicles>, C-02, C-04, C-29 Check the trouble symptom. NG Repair Replace the hydraulic unit and ABS-ECU. Repair NG Check the trouble symptom. NG NG OK Check the harness wire, and repair if necessary. D Between battery and stop lamp switch D Between stop lamp switch and ABS-ECU NG Check the harness wire, and repair if necessary. D Between stop lamp switch and ABS-ECU Probable cause Code Nos.41, 42, 43 and 44 Solenoid valve Code No.52 Valve relay problem (stays off) Code No.53 Motor relay problem (stays off) Code No.55 Motor system (seized pump motor) These codes are output if there is an open circuit or short-circuit in the ABS-ECU power supply circuit (power supply circuit for solenoid valve and motor), or the internal circuit in the hydraulic unit and ABS-ECU is defective. D Malfunction of wiring harness or connector D Malfunction of hydraulic unit and ABS-ECU NG Measure at the ABS-ECU connector A-58. D Disconnect the connector, and measure at the harness side connector. D Voltage between 22 and body earth, and between 24 and body earth OK: System voltage OK Check the trouble symptom. NG Replace the hydraulic unit and ABS-ECU. OK Check the trouble symptom. NG Repair NG Check the following connector: A-58 OK Check the following connectors: A-58, C-24 <R.H. drive vehicles> NG Repair Check the harness wire, and repair if necessary. D Between fusible link No.1 and ABS-ECU 35B-14 ABS <4WD> – Troubleshooting INSPECTION CHART FOR TROUBLE SYMPTOMS Trouble symptoms Inspection procedure No. Reference page Communication between the MUT-II and the whole system is not possible. 1 35B-14 Communication between the MUT-II and the ABS-ECU is not possible. 2 35B-15 When the ignition key is turned to “ON” (engine stopped), the ABS warning lamp does not illuminate. 3 35B-16 Even after the engine is started, the ABS warning lamp remains illuminated. 4 35B-17 Faulty ABS operation 5 35B-18 Caution 1. If steering movements are made when driving at high speed, or when driving on road surfaces with low frictional resistance, or when passing over bumps, the ABS may operate even though sudden braking is not being applied. Because of this, when getting information from the customer, check if the problem occurred while driving under such conditions as these. 2. During ABS operation, the brake pedal may vibrate or may not be able to be depressed. Such phenomena are due to intermittent changes in hydraulic pressure inside the brake line to prevent the wheels from locking and is not an abnormality. INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS Inspection Procedure 1 Communication between the MUT-II and the whole system is not possible. Probable cause The cause may be a malfunction of the power supply circuit or the earth circuit of the diagnosis connector. D Malfunction of diagnosis connector D Malfunction of wiring harness or connector NG Measure at the diagnosis connector C-35. D Voltage between 16 and body earth OK: System voltage Check the following connectors: C-35, C-76, C-77 OK Check the trouble symptom. OK NG Repair NG Check the harness wire, and repair if necessary. D Between fusible link No.2 and diagnosis connector NG Measure at the diagnosis connector C-35. D Continuity between 4 and body earth, and between 5 and body earth OK: Continuity OK Check the trouble symptom. NG Replace the MUT-II. Check the following connector: C-35 OK Check the trouble symptom. NG NG Repair Check the harness wire, and repair if necessary. D Between diagnosis connector and earth 35B-15 ABS <4WD> – Troubleshooting Inspection Procedure 2 Communication between MUT-II and the ABS-ECU is not possible. Probable cause The cause may be an open circuit in the ABS-ECU power supply circuit or an open circuit in the diagnosis output circuit. D Blown fuse D Malfunction of wiring harness or connector D Malfunction of hydraulic unit and ABS-ECU NG Measure at the diagnosis connector C-35 and the ABS-ECU connector A-58. D Disconnect the connectors, and measure at the harness side connectors. D Continuity between the following terminals ABS-ECU side – Diagnosis connector side 19 – 1 9 – 7 OK: Continuity Check the following connectors: A-58, C-28 <L.H. drive vehicles>, C-40 <R.H. drive vehicles>, C-70, C-35 OK Check the trouble symptom. NG Repair NG Check the harness wire, and repair if necessary. D Between ABS-ECU and diagnosis connector OK NG Measure at the ABS-ECU connector A-58. D Disconnect the connector, and measure at the harness side connector. D Ignition switch: ON D Voltage between 10 and body earth OK: System voltage Check the following connectors: A-58, C-40 <R.H. drive vehicles>, C-02 <R.H. drive vehicles>, C-78 <L.H. drive vehicles>, C-76 <R.H. drive vehicles>, C-74 OK Check the trouble symptom. OK NG Repair NG Check the harness wire, and repair if necessary. D Between ignition switch and ABS-ECU Measure at the ABS-ECU connector A-58. D Disconnect the connector, and measure at the harness side connector. D Continuity between 21 and body earth, and between 23 and body earth OK: Continuity OK Check the following connector: A-58 OK Check the trouble symptom. NG Replace the hydraulic unit and ABS-ECU. NG Repair NG Check the following connector: A-58 OK Check the trouble symptom. NG NG Repair Check the harness wire, and repair if necessary. D Between ABS-ECU and earth 35B-16 ABS <4WD> – Troubleshooting Inspection Procedure 3 When the ignition key is turned to “ON” (engine stopped), the ABS warning lamp does not illuminate. Probable cause The cause may be an open circuit in the lamp power supply circuit, a blown lamp, a malfunction of the ABS warning lamp relay or an open circuit between the ABS warning lamp and the earth. D D D D D Blown fuse Burn out ABS Malfunction of Malfunction of Malfunction of warning lamp bulb ABS warning lamp relay wiring harness or connector hydraulic unit and ABS-ECU NG Refer to GROUP 00 – Inspection Service Points for Blown Fuse. Fuse check Multi-purpose fuse No.6 OK NG Measure at the ABS warning lamp relay connector A-57. D Disconnect the connector, and measure at the harness side connector. D Ignition switch: ON D ABS warning lamp condition when terminal 3 is earthed. OK: Illuminates Check whether the ABS warning lamp bulb is burnt out. Replace the ABS warning lamp bulb. OK Check the following connectors: A-57, C-27 <L.H. drive vehicles>, C-40 <R.H. drive vehicles>, C-07, C-06, C-02 <L.H. drive vehicles>, C-76, C-74 ABS warning lamp relay check (Refer to P.35B-23.) NG OK NG OK OK Replace the ABS warning lamp relay. Check the trouble symptom. NG Repair NG Check the harness wire. D Between ignition switch and combination meter D Between combination meter and ABS warning lamp relay OK NG Repair Replace the combination meter. NG Measure at the ABS warning lamp relay connector A-57. D Disconnect the connector, and measure at the harness side connector. D Ignition switch: ON D Continuity between 1 and body earth OK: Continuity OK Replace the hydraulic unit and ABS-ECU. Check the following connector: A-57 OK Check the trouble symptom. NG Repair NG Check the harness wire, and repair if necessary. D Between ABS warning lamp relay and earth 35B-17 ABS <4WD> – Troubleshooting Inspection Procedure 4 Even after the engine is started, the ABS warning lamp remains illuminated. Probable cause The cause is probably a short-circuit in the ABS warning lamp illumination circuit. D D D D Malfunction Malfunction Malfunction Malfunction of of of of combination meter ABS warning lamp relay wiring harness (short circuit) hydraulic unit and ABS-ECU NOTE This trouble symptom is limited to cases where communication with the MUT-II is possible (ABS-ECU power supply is normal) and the diagnosis code is a normal diagnosis code. YES Replace the combination meter. Does the ABS warning lamp stay illuminated when the combination meter connector C-07 is disconnected and the ignition switch is turned to ON? NO NG ABS warning lamp relay check (Refer to P.35B-23.) Replace the ABS warning lamp relay. OK YES Check the harness wire, and repair if necessary. D Between combination meter and ABS warning lamp relay Does the ABS warning lamp stay illuminated when the ABS warning lamp relay connector A-57 is disconnected and the ignition switch is turned to ON? NO NG Measure at the ABS warning lamp relay connector A-57. D Disconnect the connector, and measure at the harness side connector. D Ignition switch: ON D Voltage between 5 and body earth OK: System voltage Check the following connector: A-57 OK Check the trouble symptom. NG Repair NG OK Check the harness wire, and repair if necessary. D Between ignition switch and ABS warning lamp relay NG Measure at the ABS-ECU connector A-58. D Ignition switch: ON D Voltage between 8 and body earth OK: System voltage OK Replace the hydraulic unit and ABS-ECU. Check the following connectors: A-58, A-57 OK NG Check the trouble symptom. Repair NG Check the harness wire, and repair if necessary. D Between ABS warning lamp relay and ABS-ECU 35B-18 ABS <4WD> – Troubleshooting Inspection Procedure 5 Faulty ABS operation Probable cause This varies depending on the driving conditions and the road surface conditions, so problem diagnosis is difficult. However, if a normal diagnosis code is displayed, carry out the following inspection. D D D D D D D NG Wheel speed sensor installation check Improper installation of wheel speed sensor Malfunction of wiring harness or connector Malfunction of wheel speed sensor Malfunction of ABS rotor Foreign material adhering to wheel speed sensor Malfunction of wheel bearing Malfunction of hydraulic unit and ABS-ECU Repair OK OK Wheel speed sensor output voltage check (Refer to P.35B-22.) Hydraulic unit check (Refer to P.35B-24.) NG NG Wheel speed sensor check (Refer to P.35B-30.) Replace the wheel speed sensor. OK ABS rotor check (Refer to P.35B-30.) NG Repair OK Wheel bearing check (Refer to GROUP 26 and GROUP 27 – On-vehicle Service.) NG Repair OK Check the following connectors: A-58, C-25 <L.H. drive vehicles>, C-24 <R.H. drive vehicles>, A-24, A-85, D-24, D-28 NG Repair OK Check the trouble symptom. NG Measure at the ABS-ECU connector A-58. D Disconnect the connector, and measure at the harness side connector. D Resistances between 17 and 18, 15 and 14, 4 and 5, 2 and 1 OK: 1.30 – 1.58 kΩ (The sensor harness and connector should be moved while these inspections are carried out.) OK Check the following connector: A-58 OK Check the trouble symptom. NG Replace the hydraulic unit and ABS-ECU. NG NG Check the harness wire. D Between each wheel speed sensor and ABS-ECU Repair 35B-19 ABS <4WD> – Troubleshooting DATA LIST REFERENCE TABLE The following items can be read by the MUT-II from the ABS-ECU input data. 1. When the system is normal Item No. Check item Checking requirements Normal value 11 Front-right wheel speed sensor Perform a test run 12 Front-left wheel speed sensor 13 Rear-right wheel speed sensor Vehicle speeds displayed on the speedometer MUT II are and MUT-II identical. 14 Rear-left wheel speed sensor 16 ABS-ECU power supply voltage Ignition switch: ON 9.2 – 17.5 V 32 G sensor Vehicle is stopped. 2.4 – 2.6 V Vehicle is running. 0.5 – 4.5 V Depress the brake pedal. ON Release the brake pedal. OFF 33 Stop lamp switch 2. When the ABS-ECU shut off ABS operation. When the diagnosis system stops the ABS-ECU, the MUT-II display data will be unreliable. ACTUATOR TEST REFERENCE TABLE The MUT-II activates the following actuators for testing. NOTE 1. If the ABS-ECU runs down, actuator testing cannot be carried out. 2. Actuator testing is only possible when the vehicle is stationary. ACTUATOR TEST SPECIFICATIONS Activation pattern A Solenoid B valve C 0.05 s ON Pump motor OFF Start of forced action 1s End of forced action 2s 0.01 s NOTE A: Hydraulic pressure increase B: Hydraulic pressure holds C: Hydraulic pressure decrease No. Item 01 Solenoid valve for front-right wheel 02 Solenoid valve for front-left wheel 03 Solenoid valve for rear-right wheel 04 Solenoid valve for rear-left wheel Solenoid valves and pump motors in the hydraulic unit (simple inspection mode) 35B-20 ABS <4WD> – Troubleshooting CHECK AT ABS-ECU TERMINAL VOLTAGE CHECK CHART 1. Disconnect the ABS-ECU connector. (Refer to P. 35B-27.) 2. Use the special tool to measure the voltage between each terminal and earth (terminal No.23). 3. The terminal layout is shown in the illustration. Earth terminal Check connector MB991547 Body side harness ABS-ECU Terminal No. Check item Checking requirements 3 Stop lamp switch input Ignition switch: ON 7 Input In ut from G sensor Ignition switch: ON Vehicle is horizontal 8 ABS warning lamp relay transistor output Ignition switch: ON Normal condition Stop lamp switch: ON System voltage Stop lamp switch: OFF 1 V or less 2.4 – 2.6 V When the lamp switched off is When the lamp is illuminated 9 10 19 MUT-II ABS-ECU power supply Diagnosis changeover input 2 V or less System voltage When the MUT-II is connected Serial communication with MUT-II When the MUT-II is not connected 1 V or less Ignition switch: ON System voltage Ignition switch: START 0V When the MUT-II is connected 0V When the MUT-II is not connected Approx. 12 V 20 G sensor earth Always 0V 22 Solenoid valve power supply Always System voltage 24 Motor power supply Always System voltage 35B-21 ABS <4WD> – Troubleshooting RESISTANCE AND CONTINUITY BETWEEN HARNESS-SIDE CONNECTOR TERMINALS 1. Turn the ignition key to the LOCK (OFF) position. 2. Disconnect the ABS-ECU connector. (Refer to P. 35B-27.) 3. Use the special tool to check the resistance and continuity between the terminals indicated in the table below. 4. The terminal layout is shown in the illustration. Check connector MB991547 Body side harness ABS-ECU ABS–ECU terminal No. Signal Normal condition 1–2 Wheel speed sensor (rear left) 1.30 – 1.58 kΩ 4–5 Wheel speed sensor (rear right) 14 – 15 Wheel speed sensor (front left) 17 – 18 Wheel speed sensor (front right) 21 – Body earth Earth 23 – Body earth Earth Continuity 35B-22 ABS <4WD> – On-vehicle Service ON-VEHICLE SERVICE WHEEL SPEED SENSOR OUTPUT VOLTAGE CHECK Check connector MB991547 Body side harness 1. Lift up the vehicle and release the parking brake. 2. Disconnect the ABS-ECU connector and then connect the special tool to the harness side connector. (Refer to P. 35B-27.) 3. Rotate the wheel to be measured at approximately 1/2–1 rotation per second, and check the output voltage using a circuit tester or an oscilloscope. Wheel speed sensor Front left Front right Rear left Rear right Terminal No. 15 17 2 4 14 18 1 5 Output voltage ABS-ECU When measuring with a circuit tester: 42 mV or more When measuring with an oscilloscope: 120 mV p-p or more 4. The followings are suspected if the output voltage is lower than the value described above. Check the wheel speed sensor, and replace if necessary. D Too large clearance between the pole piece of the wheel speed sensor and ABS rotor D Faulty wheel speed sensor When turning by hand When idling (5 – 6 km/h), 1st gear (M/T) or D range (A/T) 10.0 ms/DIV 1 V/DIV Inspecting Waveforms With An Oscilloscope Use the following method to observe the output voltage waveform from each wheel speed sensor with an oscilloscope. D Start the engine, and rotate the rear wheels by engaging 1st gear (vehicles with manual transmission) or D range (vehicles with automatic transmission). Turn the front wheels manually so that they rotate at a constant speed. NOTE 1. The waveform measurements can also be taken while the vehicle is actually moving. 2. The output voltage will be small when the wheel speed is low, and similarly it will be large when the wheel speed is high. 35B-23 ABS <4WD> – On-vehicle Service Points In Waveform Measurement Symptom Probable causes Remedy Too small or zero waveform amplitude Faulty wheel speed sensor Replace sensor Waveform amplitude fluctuates excessively (this is no problem roblem if the minimum amplitude is 100 mV or more) Axle hub eccentric or with large runout Replace hub Faulty ABS-ECU earth Repair Noisy or disturbed waveform Open circuit in sensor Replace sensor Open circuit in harness Correct harness Incorrectly mounted wheel speed sensor Mount correctly ABS rotor with missing or damaged teeth Replace ABS rotor Caution Because the wheel speed sensor cables move together with the front and rear suspension, they vibrate greatly when driving over poor road surfaces. As a result, the sensor harnesses should also be shaken when monitoring of output waveforms of the wheel speed sensors in order to simulate conditions such as driving over poor road surfaces. <L.H. drive vehicles> Hydraulic unit and ABS-ECU ABS WARNING LAMP RELAY CONTINUITY CHECK Battery voltage Terminal No. 1 Power is not supplied Power is supplied <R.H. drive vehicles> Hydraulic unit and ABS-ECU 2 3 5 35B-24 ABS <4WD> – On-vehicle Service HYDRAULIC UNIT CHECK 1. Jack up the vehicle and support the vehicle with rigid racks placed at the specified jack-up points or place the wheels which are checked on the rollers of the braking force tester. Caution (1) The roller of the braking force tester and the tyre should be dry during testing. (2) When testing the front brakes, apply the parking brake, and when testing the rear brakes, stop the front wheels by chocking them. 2. Turn the ignition key to the LOCK (OFF) position and set the MUT-II. Caution Turn the ignition key to the LOCK (OFF) position before connecting or disconnecting the MUT-II. 3. After checking that the shift lever <M/T> or the selector lever <A/T> is in neutral, start the engine. 4. Use the MUT-II to force-drive the actuator. NOTE (1) During the actuator test, the ABS warning lamp will illuminate and the anti-skid control will be cancelled. (2) When the ABS has been interrupted by the fail-safe function, the MUT-II actuator testing cannot be used. 5. Turn the wheel by hand and check the change in braking force when the brake pedal is depressed. When using the braking force tester, depress the brake pedal until the braking force is at the following values, and check that the braking force decreases when the actuator is force-driven. Front wheel 785 – 981 N Rear wheel 588 – 784 N The result should be as shown in the following diagram. Pedal operation Depressed Released Increase in pressure Solenoid valve position Steady pressure Reduction in pressure Checking the brake force MUT-II actuator test (Item No. 01, 02, 03, 04) start Lock Drag force when the pedal is free 2 seconds 1 seconds Approx. 0.05 seconds ABS <4WD> – On-vehicle Service 35B-25 6. If the result of inspection is abnormal, correct according to the “Diagnosis Table”. Diagnosis Table No. Operation Judgement – Normal Judgement – Abnormal Probable cause Remedy 01 (1) Depress brake pedal to lock wheel. (2) Using the MUT-II, select the wheel to be checked and force the actuator to operate. (3) Turn the selected wheel manually to check the change of brake force. Brake force released for 3 seconds after locking locking. Wheel does not lock when brake pedal is depressed pressed. Clogged brake line other than hydraulic unit Check and clean brake line Clogged hydraulic circuit in hydraulic unit Replace hydraulic unit assembly Incorrect hydraulic unit brake tube connection Connect correctly Hydraulic unit solenoid valve not functioning correctly Replace hydraulic unit assembly 02 03 04 Brake force is not released 7. After inspection, disconnect the MUT-II immediately after turning the ignition switch to OFF. REMEDY FOR A FLAT BATTERY When booster cables are used to start the engine when the battery is completely flat and then the vehicle is immediately driven without waiting for the battery to recharge itself to some extent, the engine may misfire, and driving might not be possible. This happens because ABS consumes a great amount of current for its self-check function; the remedy is to either allow the battery to recharge sufficiently, or to disconnect the ABS-ECU connector, thus disabling the anti-skid brake system. The ABS warning lamp will illuminate when the ABS-ECU connector is disconnected. After the battery has sufficiently recharged, connect the ABS-ECU connector and restart the engine; then check to be sure the ABS warning lamp is not illuminated. Lock lever Hydraulic unit and ABS-ECU DISCONNECTING ABS-ECU CONNECTOR Move the lock lever of the ABS-ECU connector as shown in the illustration, and then disconnect the ABS-ECU connector. 35B-26 ABS <4WD> – Hydraulic Unit and ABS-ECU HYDRAULIC UNIT AND ABS-ECU REMOVAL AND INSTALLATION Pre-removal Operation D Brake Fluid Draining D Air Cleaner Removal (Refer to GROUP 15.) Post-installation Operation D Brake Fluid Supplying and Brake Line Bleeding (Refer to GROUP 35A – On-vehicle Service.) D Hydraulic Unit Inspection (Refer to P.35B-24.) D Air Cleaner Installation (Refer to GROUP 15.) <L.H. drive vehicles> 3 3 4 15 Nm 2 5 1 ABS <4WD> – Hydraulic Unit and ABS-ECU 35B-27 <R.H. drive vehicles> 3 3 4 15 Nm 2 5 1 Removal steps 1. ABS warning lamp relay AA" 2. Harness connector "AA 3. Brake pipe connection AB" 4. Hydraulic unit and ABS-ECU 5. Hydraulic unit bracket assembly REMOVAL SERVICE POINTS Lock lever Hydraulic unit and ABS-ECU AA" HARNESS CONNECTOR DISCONNECTION Move the lock lever of the ABS-ECU connector as shown in the illustration, and then disconnect the harness connector. 35B-28 ABS <4WD> – Hydraulic Unit and ABS-ECU AB" HYDRAULIC UNIT AND ABS-ECU REMOVAL Caution 1. The hydraulic unit assembly is heavy, and so care should be taken when removing it. 2. The hydraulic unit assembly is not to be disassembled; its nuts and bolts should absolutely not be loosened. 3. The hydraulic unit assembly must not be dropped or otherwise subjected to impact shocks. 4. The hydraulic unit assembly must not be turned upside down or laid on its side. 5 1 2 INSTALLATION SERVICE POINT 6 3 4 "AA BRAKE PIPE CONNECTION Connect the pipes to the hydraulic unit assembly as shown in the illustration. 1. To the proportioning valve (Rear brake, LH) 2. To the proportioning valve (Rear brake, RH) 3. From the master cylinder (Primary) 4. From the master cylinder (Secondary) 5. To the front brake (RH) 6. To the front brake (LH) 35B-29 ABS <4WD> – Wheel Speed Sensor WHEEL SPEED SENSOR REMOVAL AND INSTALLATION Post-installation Operation Wheel Speed Sensor Output Voltage Check (Refer to P.35B-22.) <FRONT> <REAR> 3 1 4 2 AA" AA" 1. Front wheel speed sensor 2. Front ABS rotor (Refer to GROUP 26 – Drive Shaft.) 3. Rear wheel speed sensor 4. Rear ABS rotor (Refer to GROUP 27 – Axle Shaft.) NOTE The front ABS rotor is integrated with the drive shaft. Do not disassemble it. REMOVAL SERVICE POINT AA" FRONT WHEEL SPEED SENSOR/REAR WHEEL SPEED SENSOR REMOVAL Pole piece Caution Do not strike the pole piece at the tip of the wheel speed sensor against the ABS rotor tooth surface or other parts when removing the wheel speed sensor. 35B-30 ABS <4WD> – Wheel Speed Sensor INSPECTION CHECK OF RESISTANCE BETWEEN WHEEL SPEED SENSOR TERMINALS Caution The pole piece can become magnetized because of the magnet built into the wheel speed sensor, with the result that metallic foreign material easily adheres to it. Moreover, the pole piece may not be able to function to correctly sense the wheel rotation speed if it is damaged. 1. Measure the resistance between the wheel speed sensor terminals. Standard value: 1.30 – 1.58 kΩ If the internal resistance of the wheel speed sensor is not within the standard value, replace with a new wheel speed sensor. 2. Check the wheel speed sensor cable for breakage, damage or disconnection; replace with a new one if a problem is found. NOTE When checking for cable damage, remove the cable clamp part from the body and then bend and pull the cable near the clamp to check whether or not temporary disconnection occurs. WHEEL SPEED SENSOR INSULATION INSPECTION 1. Remove all connections from the wheel speed sensor, and then measure the resistance between terminals 1 and 2 and the body of the wheel speed sensor. Standard value: 100 kΩ or more 2. If the speed sensor insulation resistance is outside the standard value range, replace with a new speed sensor. ABS ROTOR CHECK Check whether ABS rotor teeth are broken or deformed, and, if so, replace the B.J. assembly or the ABS rotor. ABS <4WD> – G Sensor 35B-31 G SENSOR REMOVAL AND INSTALLATION Caution Do not drop the G sensor or subject it to any shocks. Pre-removal and Post-installation Operation Rear floor console removal and installation (Refer to Group 52A.) 5 Nm G sensor INSPECTION Label 1. Remove the G sensor. 2. Connect the special tool between the disconnected connectors, and then place the G sensor horizontally as shown in the illustration. 3. Turn on the ignition switch, and then measure the voltage between terminal No.2 and body earth. Standard value: 2.4 – 2.6 V MB991348 Label 4. Face the labeled surface straight down with the special tool still connected. Measure the voltage between terminal No.2 and body earth with the labeled surface faced straight down. Standard value: 3.3 – 3.7 V 5. If not within the standard value, check the power supply line and earth condition, and then replace the G sensor. NOTES 35B-1 ANTI-SKID BRAKING SYSTEM (ABS) <4WD> CONTENTS GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 ON-VEHICLE SERVICE . . . . . . . . . . . . . . . . . . . . 14 Outline of Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Wheel Speed Sensor Output Voltage Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 GENERAL INFORMATION . . . . . . . . . . . . . . . . . . 2 HYDRAULIC UNIT AND ABS-ECU . . . . . . . . . 15 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . 5 35B-2 ABS <4WD> – General/General Information GENERAL OUTLINE OF CHANGES The hydraulic unit (integrated with the ABS-ECU) has been reshaped. In addition, the troubleshooting has been changed due to the change on the ABS-ECU connector. The Electronic Brake-force Distribution (EBD) has been adopted. The EBD makes it possible to maintain the maximum amount of braking force for the rear wheels even when the vehicle’s load is unevenly distributed GENERAL INFORMATION EBD CONTROL In ABS, electronic control method is used whereby the rear wheel brake hydraulic pressure during braking is regulated by rear wheel control solenoid valves in accordance with the vehicle’s rate of deceleration and the front and rear wheel slippage which are calculated from the signals received from the various wheel sensors. EBD control is a control system which provides a high level of control for both vehicle braking force and vehicle stability. The system has the following features. Because the system provides the optimum rear wheel braking force regardless of the vehicle laden condition and the condition of the road surface, the system reduces the required pedal depression force, particularly when the vehicle is heavily laden or driving on road surfaces with high frictional coefficients. Because the duty placed on the front brakes has been reduced, the increases in pad temperature can be controlled during front brakes applying to improve the wear resistance characteristics of the pad. Control valves such as the proportioning valve are no longer required. HYDRAULIC UNIT New Old Hydraulic unit Hydraulic unit 35B-3 ABS<4WD> – General Information ABS-ECU EBD HYDRAULIC PRESSURE CONTROL The procedures are the same as that used in PAJERO except for the items shown below. Item PAJERO-PININ PAJERO EBD control condition When the difference between the rear wheel speed and the vehicle speed exceeds the set value. When the difference between the rear wheel speed and the front wheel speed exceeds the set value. <PAJERO-PININ> Rear wheel speed sensor Front wheel speed sensor Vehicle speed EBD control Set value of EBD slip ratio Speed Set value of ABS slip ratio ABS control (Rear wheel) ABS control (Front wheel) Time <PAJERO> Rear wheel speed sensor Front wheel speed sensor Vehicle speed Set value of EBD slip ratio Speed Set value of ABS slip ratio EBD control ABS control (Rear wheel) ABS control (Front wheel) Time 35B-4 ABS<4WD> – General Information FAIL-SAFE FUNCTION The procedures are the same as that used in PAJERO except for the items shown below. Item PAJERO-PININ PAJERO Warning lamp during fail-safe operation ABS warning lamp Brake warning lamp Diagnosis g code d No. N Item 11 Open circuit or short-circuit in wheel speed sensor (FR) 12 Open circuit or short-circuit in wheel speed sensor (FL) 13 Open circuit or short-circuit in wheel speed sensor (RR) 14 Open circuit or short-circuit in wheel speed sensor (RL) 15 Problem with any one of the four wheel speed sensors 16 Action during fail-safe operation ABS control EBD control ABS warning lamp If faulty wheels include two rear wheels: C t l stopped t d iin allll Control wheels Other than the above: Control stopped in faulty wheels If faulty wheels include two rear wheels: C t l stopped t d Control Other than the above: Control carried out Illuminated Abnormal drop or rise in ABS-ECU power supply voltage Control stopped Control stopped Illuminated 21 Wheel speed sensor (FR) system Wheel speed sensor (FL) system 23 Wheel speed sensor (RR) system If faulty wheels include two rear wheels: C t l stopped t d Control Other than the above: Control carried out Illuminated 22 If faulty wheels include two rear wheels: C t l stopped t d iin allll Control wheels Other than the above: Control stopped in faulty wheels 24 Wheel speed sensor (RL) system 32 G sensor system Control stopped Control carried out Illuminated 33 Stop lamp switch system Control stopped Control carried out Illuminated 41 Solenoid valve (FR) system System y interrupted System y interrupted Illuminated 42 Solenoid valve (FL) system 43 Solenoid valve (RR) system 44 Solenoid valve (RL) system 51 Valve relay ON problem Control stopped Control carried out Illuminated 52 Valve relay OFF problem System interrupted System interrupted Illuminated 53 Motor relay OFF problem Control stopped Control carried out Illuminated 54 Motor relay ON problem System interrupted Control carried out Illuminated 55 Motor system Control stopped Control carried out Illuminated 63 ABS-ECU abnormality System interrupted System interrupted Illuminated NOTE Control stopped: Control is not carried out until the ignition switch is turned to the “LOCK” (OFF) position. However, if the problem returns to normal, control is carried out again. System interrupted: Control is not carried out until the valve relay turns off and the ignition switch is turned to the “LOCK” (OFF) position. 35B-5 ABS <4WD> – Troubleshooting TROUBLESHOOTING INSPECTION CHART FOR DIAGNOSIS CODES Diagnosis code No. Inspection item Reference page 11 Front right wheel speed sensor (Open circuit or short circuit) 35B-6 12 Front left wheel speed sensor (Open circuit or short circuit) 35B-6 13 Rear right wheel speed sensor (Open circuit or short circuit) 35B-6 14 Rear left wheel speed sensor (Open circuit or short circuit) 35B-6 15 Wheel speed sensor (Abnormal output signal) – 16* ABS-ECU power supply system (Abnormal voltage drop or rise) 35B-7 21 Front right wheel speed sensor 35B-6 22 Front left wheel speed sensor 35B-6 23 Rear right wheel speed sensor 35B-6 24 Rear left wheel speed sensor 35B-6 32 G sensor system 35B-7 33 Stop lamp switch system – 41 Front right solenoid valve 42 Front left solenoid valve 43 Rear right solenoid valve 44 Rear left solenoid valve 51 Valve relay problem (stays on) – 52 Valve relay problem (stays off) or ABS-ECU power supply system problem 35B-8 53 Motor relay problem (stays off) or ABS-ECU power supply system problem 54 Motor relay problem (stays on) – 55 Motor system (seized pump motor) or ABS-ECU power supply system problem 35B-8 63 ABS-ECU – The diagnosis codes are output when there is no response to the drive signals for respective solenoid ABS ECU power valves or the ABS-ECU supply system is defective. NOTE *: Turning the ignition switch to ACC will erase the diagnosis code No.16. 35B-8 35B-6 ABS <4WD> – Troubleshooting INSPECTION PROCEDURE FOR DIAGNOSIS CODES Probable cause Code Nos.11, 12, 13 and 14 Wheel speed sensor (open circuit or short circuit) Code Nos.21, 22, 23 and 24 Wheel speed sensor Code Nos. 11, 12, 13 and 14 are output if the ABS-ECU detects an open circuit or short-circuit in the (+) wire or (–) wire in any one of the four wheel speed sensors. Malfunction of wheel speed sensor Malfunction of wiring harness or connector Malfunction of hydraulic unit and ABS-ECU Code Nos. 21, 22, 23 and 24 are output in the following cases. When there is no input from any one of the four wheel speed sensors when travelling at several km/h or more, even though open circuit can not be verified. When a chipped or blocked-up ABS rotor is detected and if the anti-lock system operates continuously because a malfunctioning sensor or a warped ABS rotor is causing sensor output to drop. NG Wheel speed sensor installation check OK NG Measure at the ABS-ECU connector A-58. Disconnect the connector, and measure at the harness side connector. Resistances between 26 and 27, 4 and 5, 2 and 1, 24 and 23 OK: 1.30 – 1.58 kΩ NG sensor NG Check the following connectors: A-58, C-25<L.H. drive vehicles>, C-24<R.H. drive vehicles>, A-24, A-85, D-24, D-28 OK NG speed Wheel speed sensor check Replace Wheel speed sensor output voltage check (Refer to P.35B-14.) Wheel check Repair OK OK OK Malfunction of wheel speed sensor Malfunction of wiring harness or connector Malfunction of ABS rotor Too much gap between the sensor and the ABS rotor Malfunction of hydraulic unit and ABS-ECU Malfunction of wheel bearing Replace Check the trouble symptom. NG Repair NG OK NG ABS rotor check OK Wheel bearing check (Refer to GROUP 26 and GROUP 27 – On-vehicle Service.) Check the following connector: A-58 OK Check the trouble symptom. NG Replace the hydraulic unit and ABS-ECU. NG Repair Replace Check the harness wire, and repair if necessary. Between each wheel speed sensor and ABS-ECU 35B-7 ABS <4WD> – Troubleshooting Code No.16 ABS-ECU power supply system (abnormal voltage drop or rise) Probable cause This code is output if the ABS-ECU power supply voltage drops below or rises above the rated values. Furthermore, turning the ignition switch to ACC will erase this code. Malfunction of battery Malfunction of wiring harness or connector Malfunction of hydraulic unit and ABS-ECU Caution If battery voltage drops or rises during inspection, this code will be output as well. If the voltage returns to standard value, this code is no longer output. Before carrying out the following inspection, check the battery level, and refill it if necessary. NG Measure at the ABS-ECU connector A-58. Disconnect the connector, and measure at the harness side connector. Start the engine. Voltage between 32 and body earth OK: System voltage Check the following connectors: A-58, C-40 <R.H. drive vehicles>, C-02 <R.H. drive vehicles>, C-78 <L.H. drive vehicles>, C-76 <R.H. drive vehicles>, C-74 OK NG OK Check the trouble symptom. Check the following connector: A-58 OK Check the trouble symptom. NG Replace the hydraulic unit and ABS-ECU. NG Repair NG Repair Check the harness wire, and repair if necessary. Between ignition switch and ABS-ECU 35B-8 ABS <4WD> – Troubleshooting Code No.32 G sensor system Probable cause This code is output in the following cases. G sensor output voltage is less than 0.5 V or more than 4.5 V. (An open or short circuit is present in the G sensor circuit.) G sensor output voltage does not change. (G sensor output voltage is abnormal.) Malfunction of G sensor Malfunction of wiring harness or connector Malfunction of hydraulic unit and ABS-ECU NG G sensor check Replace OK Measure at the G sensor connector D-29. Disconnect the connector, and measure at the harness side connector. Ignition switch: ON Voltage between 1 and body earth OK: System voltage NG Check the following connector: D-29 NG OK Check the trouble symptom. Repair NG OK Check the harness wire, and repair if necessary. Between ignition switch and G sensor Measure at the ABS-ECU connector A-58. Disconnect the connector, and measure at the harness side connector. Ignition switch: ON Voltage between 9 and 6 OK: 2.4 – 2.6 V (When labeled surface is faced to vertical direction) NG Check the following connectors: A-58, C-25 <L.H. drive vehicles>, D-29 Check the trouble symptom. Repair NG OK Check the following connector: A-58 OK Check the harness wire, and repair if necessary. Between G sensor and ABS-ECU NG Check the trouble symptom. NG OK Repair NG Replace the hydraulic unit and ABS-ECU. Probable cause Code Nos.41, 42, 43 and 44 Solenoid valve Code No.52 Valve relay problem (stays off) Code No.53 Motor relay problem (stays off) Code No.55 Motor system (seized pump motor) These codes are output if there is an open circuit or short-circuit in the ABS-ECU power supply circuit (power supply circuit for solenoid valve and motor), or the internal circuit in the hydraulic unit and ABS-ECU is defective. Malfunction of wiring harness or connector Malfunction of hydraulic unit and ABS-ECU NG Measure at the ABS-ECU connector A-58. Disconnect the connector, and measure at the harness side connector. Voltage between 34 and body earth, and between 12 and body earth OK: System voltage OK Check the trouble symptom. NG Replace the hydraulic unit and ABS-ECU. OK Check the trouble symptom. NG Repair NG Check the following connector: A-58 OK Check the following connectors: A-58, C-24 <R.H. drive vehicles> NG Repair Check the harness wire, and repair if necessary. Between fusible link No.1 and ABS-ECU 35B-9 ABS <4WD> – Troubleshooting INSPECTION CHART FOR TROUBLE SYMPTOMS Trouble symptoms Inspection procedure No. Reference page Communication between the MUT-II and the whole system is not possible. 1 – Communication between the MUT-II and the ABS-ECU is not possible. 2 35B-10 When the ignition key is turned to “ON” (engine stopped), the ABS warning lamp does not illuminate. 3 – Even after the engine is started, the ABS warning lamp remains illuminated. 4 35B-11 Faulty ABS operation 5 35B-12 Caution 1. If steering movements are made when driving at high speed, or when driving on road surfaces with low frictional resistance, or when passing over bumps, the ABS may operate even though sudden braking is not being applied. Because of this, when getting information from the customer, check if the problem occurred while driving under such conditions as these. 2. During ABS operation, the brake pedal may vibrate or may not be able to be depressed. Such phenomena are due to intermittent changes in hydraulic pressure inside the brake line to prevent the wheels from locking and is not an abnormality. 35B-10 ABS <4WD> – Troubleshooting INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS Inspection Procedure 2 Communication between MUT-II and the ABS-ECU is not possible. Probable cause The cause may be an open circuit in the ABS-ECU power supply circuit or an open circuit in the diagnosis output circuit. Blown fuse Malfunction of wiring harness or connector Malfunction of hydraulic unit and ABS-ECU NG Measure at the diagnosis connector C-35 and the ABS-ECU connector A-58. Disconnect the connectors, and measure at the harness side connectors. Continuity between the following terminals ABS-ECU side – Diagnosis connector side 19 – 1 21 – 7 OK: Continuity Check the following connectors: A-58, C-28 <L.H. drive vehicles>, C-40 <R.H. drive vehicles>, C-70, C-35 OK Check the trouble symptom. NG Repair NG Check the harness wire, and repair if necessary. Between ABS-ECU and diagnosis connector OK NG Measure at the ABS-ECU connector A-58. Disconnect the connector, and measure at the harness side connector. Ignition switch: ON Voltage between 32 and body earth OK: System voltage Check the following connectors: A-58, C-40 <R.H. drive vehicles>, C-02 <R.H. drive vehicles>, C-78 <L.H. drive vehicles>, C-76 <R.H. drive vehicles>, C-74 OK Check the trouble symptom. OK NG Repair NG Check the harness wire, and repair if necessary. Between ignition switch and ABS-ECU Measure at the ABS-ECU connector A-58. Disconnect the connector, and measure at the harness side connector. Continuity between 33 and body earth, and between 11 and body earth OK: Continuity OK Check the following connector: A-58 OK Check the trouble symptom. NG Replace the hydraulic unit and ABS-ECU. NG Repair NG Check the following connector: A-58 OK Check the trouble symptom. NG NG Repair Check the harness wire, and repair if necessary. Between ABS-ECU and earth 35B-11 ABS <4WD> – Troubleshooting Inspection Procedure 4 Even after the engine is started, the ABS warning lamp remains illuminated. Probable cause The cause is probably a short-circuit in the ABS warning lamp illumination circuit. Malfunction Malfunction Malfunction Malfunction of of of of combination meter ABS warning lamp relay wiring harness (short circuit) hydraulic unit and ABS-ECU NOTE This trouble symptom is limited to cases where communication with the MUT-II is possible (ABS-ECU power supply is normal) and the diagnosis code is a normal diagnosis code. YES Replace the combination meter. Does the ABS warning lamp stay illuminated when the combination meter connector C-07 is disconnected and the ignition switch is turned to ON? NO NG ABS warning lamp relay check Replace the ABS warning lamp relay. OK YES Check the harness wire, and repair if necessary. Between combination meter and ABS warning lamp relay Does the ABS warning lamp stay illuminated when the ABS warning lamp relay connector A-57 is disconnected and the ignition switch is turned to ON? NO NG Measure at the ABS warning lamp relay connector A-57. Disconnect the connector, and measure at the harness side connector. Ignition switch: ON Voltage between 5 and body earth OK: System voltage Check the following connector: A-57 OK Check the trouble symptom. NG Repair NG OK Check the harness wire, and repair if necessary. Between ignition switch and ABS warning lamp relay NG Measure at the ABS-ECU connector A-58. Ignition switch: ON Voltage between 22 and body earth OK: System voltage OK Replace the hydraulic unit and ABS-ECU. Check the following connectors: A-58, A-57 OK NG Check the trouble symptom. Repair NG Check the harness wire, and repair if necessary. Between ABS warning lamp relay and ABS-ECU 35B-12 ABS <4WD> – Troubleshooting Inspection Procedure 5 Faulty ABS operation Probable cause This varies depending on the driving conditions and the road surface conditions, so problem diagnosis is difficult. However, if a normal diagnosis code is displayed, carry out the following inspection. NG Wheel speed sensor installation check Improper installation of wheel speed sensor Malfunction of wiring harness or connector Malfunction of wheel speed sensor Malfunction of ABS rotor Foreign material adhering to wheel speed sensor Malfunction of wheel bearing Malfunction of hydraulic unit and ABS-ECU Repair OK OK Wheel speed sensor output voltage check (Refer to P.35B-14.) Hydraulic unit check NG NG Wheel speed sensor check Replace the wheel speed sensor. OK NG ABS rotor check Repair OK Wheel bearing check (Refer to GROUP 26 and GROUP 27 – On-vehicle Service.) NG Repair OK Check the following connectors: A-58, C-25 <L.H. drive vehicles>, C-24 <R.H. drive vehicles>, A-24, A-85, D-24, D-28 NG Repair OK Check the trouble symptom. NG Measure at the ABS-ECU connector A-58. Disconnect the connector, and measure at the harness side connector. Resistances between 26 and 27, 4 and 5, 24 and 23, 2 and 1 OK: 1.30 – 1.58 kΩ (The sensor harness and connector should be moved while these inspections are carried out.) OK Check the following connector: A-58 OK Check the trouble symptom. NG Replace the hydraulic unit and ABS-ECU. NG NG Check the harness wire. Between each wheel speed sensor and ABS-ECU Repair 35B-13 ABS <4WD> – Troubleshooting CHECK AT ABS-ECU TERMINAL VOLTAGE CHECK CHART 1. Measure the voltages between the respective terminal and earth. 2. The terminal layout is shown in the illustration. Terminal No. Check item Checking requirements 3 Stop lamp switch input Ignition switch: ON Normal condition Stop lamp switch: ON System voltage Stop lamp switch: OFF 1 V or less 6 G sensor earth Always 0V 9 Input In ut from G sensor Ignition switch: ON Vehicle is horizontal 2.4 – 2.6 V 12 Solenoid valve power supply Always System voltage 19 Diagnosis changeover input When the MUT-II is connected 0V When the MUT-II is not connected Approx. 12 V When the MUT-II is connected Serial communication with MUT-II When the MUT-II is not connected 1 V or less 21 22 MUT-II ABS warning lamp relay transistor output Ignition switch: ON When the lamp switched off is When the lamp is illuminated 32 34 ABS-ECU power supply Motor power supply 2 V or less System voltage Ignition switch: ON System voltage Ignition switch: START 0V Always System voltage RESISTANCE AND CONTINUITY BETWEEN HARNESS-SIDE CONNECTOR TERMINALS 1. Turn the ignition key to the LOCK (OFF) position. 2. Disconnect the ABS-ECU connector. 3. Check the resistance and continuity between the terminals indicated in the table below. 4. The terminal layout is shown in the illustration. 35B-14 ABS <4WD> – Troubleshooting/On-vehicle Service ABS-ECU terminal No. Signal Normal condition 1–2 Wheel speed sensor (rear left) 1.30 – 1.58 kΩ 23 – 24 Wheel speed sensor (rear right) 4–5 Wheel speed sensor (front left) 26 – 27 Wheel speed sensor (front right) 11 – Body earth Earth 33 – Body earth Earth Continuity ON-VEHICLE SERVICE WHEEL SPEED SENSOR OUTPUT VOLTAGE CHECK 1. Lift up the vehicle and release the parking brake. 2. Disconnect the ABS-ECU connector. 3. Rotate the wheel to be measured at approximately 1/2–1 rotation per second, and check the output voltage using a circuit tester or an oscilloscope. Wheel speed sensor Front left Front right Rear left Rear right Terminal No. 4 26 2 24 5 27 1 23 Output voltage When measuring with a circuit tester: 42 mV or more When measuring with an oscilloscope: 120 mV p-p or more 4. The followings are suspected if the output voltage is lower than the value described above. Check the wheel speed sensor, and replace if necessary. Too large clearance between the pole piece of the wheel speed sensor and ABS rotor Faulty wheel speed sensor 35B-15 ABS <4WD> – Hydraulic Unit and ABS-ECU HYDRAULIC UNIT AND ABS-ECU REMOVAL AND INSTALLATION Pre-removal Operation Brake Fluid Draining Air Cleaner Removal (Refer to GROUP 15.) Post-installation Operation Brake Fluid Supplying and Brake Line Bleeding (Refer to GROUP 35A – On-vehicle Service.) Hydraulic Unit Inspection Air Cleaner Installation (Refer to GROUP 15.) <L.H. drive vehicles> 3 3 4 15 Nm 3 2 5 1 35B-16 ABS <4WD> – Hydraulic Unit and ABS-ECU <R.H. drive vehicles> 15 Nm 3 3 2 4 1 Removal steps 1. ABS warning lamp relay A 2. Harness connector A 3. Brake pipe connection B 4. Hydraulic unit and ABS-ECU 3 2 5 5. Hydraulic unit bracket assembly NOTE The removal service points are the same as before. INSTALLATION SERVICE POINT 1 4 6 5 A BRAKE PIPE CONNECTION Connect the pipes to the hydraulic unit assembly as shown in the illustration. 1. To the front brake (L.H.) 2. To the proportioning valve (Rear brake, R.H.) 3. To the proportioning valve (Rear brake, L.H.) 4. From the master cylinder (Primary) 5. From the master cylinder (Secondary) 6. To the front brake (R.H.)
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