35B-1 GROUP 35B CONTENTS GENERAL INFORMATION . . . . . . . . CONSTRUCTION DESCRIPTION . . . 35B-2 35B-6 SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . . 35B-6 ABS-ECU. . . . . . . . . . . . . . . . . . . . . . . . . . . 35B-6 FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS) 35B-2 GENERAL INFORMATION GENERAL INFORMATION M2351000100379 FEATURES EBD CONTROL The ABS ensures directional stability and controllability during hard braking. For vehicles with this type of ABS, 4 sensors (4 channels) are installed on front and rear wheels allowing independent left and right control. The system has the following features: NOTE: On vehicles with active stability control system, the ABS system is controlled by the ABS/active stability control system-ECU. For the system construction, refer to GROUP 35C, General Information P.35C-2. • EBD (Electronic Brake-force Distribution system) control has been added to provide the ideal braking force for the rear wheels. • Magnetic encoder for wheel speed detection has been installed as a sensing device instead of the rotor. • For wiring harness saving and secure data communication, CAN* bus has been adopted as a tool of communication with another ECU. NOTE: *: For more information about CAN (Controller Area Network), refer to Group 54CP.54C-2. In ABS, electronic control is used so 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 ABS 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 vehicle load conditions and the condition of the road surface, the system reduces the required pedal depression force, particularly when the vehicle is heavily loaded or driven on road surfaces with high frictional coefficients. • Because the duty placed on the front brakes is reduced, the increases in pad temperature can be controlled during brakes application to improve the wear resistance characteristics of the pad. • Control valves such as the proportioning valve are not required. SPECIFICATIONS Item Specification ABS control method 4-sensor, 4-channel Wheel speed sensor Magnetic encoder Type Front 86 (N pole:43 S pole:43) Rear 86 (N pole:43 S pole:43) Semiconductor FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS) 35B-3 GENERAL INFORMATION CONSTRUCTION DIAGRAM 4 5 AC311642 3, 7 6 1 2 AC311643 1 AC311644AB Name of part Number Outline of function Sensor Wheel speed sensor 1 Sends alternating current signals at frequencies which are proportional to the rotation speeds of each wheel to the ABS-ECU. Stop lamp switch 2 Sends a signal to the ABS-ECU to indicate whether the brake pedal is depressed or not. 3 Drives the solenoid valves according to signals from the ABS-ECU in order to control the brake hydraulic pressure for each wheel. ABS warning lamp 4 Illuminates in response to signals from the ABS-ECU when a problem develops in the system. Brake warning lamp 5 Illuminates in response to signals from the ABS-ECU when a problem develops in the EBD system. 6 Outputs the diagnosis codes and allows communication with the MUT-III. Actuator Hydraulic unit Diagnosis connector 35B-4 FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS) GENERAL INFORMATION Name of part Number Outline of function ABS-ECU 7 Controls actuators (described above) based on the signals coming from each sensor. Controls the self-diagnosis and fail-safe functions. Controls the diagnostic function (MUT-III compatible). SYSTEM CONFIGURATION DIAGRAM Engine-ECU <M/T> or Engine-A-M/T-ECU* <Automated manual transmission> Front right solenoid valve (out) Front-left wheel speed sensor Rear-left wheel speed sensor Rear-right wheel speed sensor Front right solenoid valve (in) Front left solenoid valve (out) Front-right wheel speed sensor Brake fluid level switch Front left solenoid valve (in) Rear right solenoid valve (out) Stop lamp switch (two systems) ABS-ECU Parking lever switch Rear right solenoid valve (in) Rear left solenoid valve (out) Rear left solenoid valve (in) ABS-ECU power supply Brake warning lamp ABS warning lamp Diagnosis connector Stop lamp switch (two systems) Brake fluid level switch Front-right wheel (FR) Rear-right wheel (RR) Front-right wheel speed sensor Rear-right wheel speed sensor Hydraulic unit (HU) Parking lever switch Front-left wheel speed sensor Front-left wheel (FL) NOTE: Broken lines show CAN-bus line. Rear-left wheel speed sensor Rear-left wheel (RL) AC314135AB NOTE: Engine-A-M/T-ECU*: Engine Automated Manual Transmission Electronic Control Unit FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS) 35B-5 GENERAL INFORMATION ABS ELECTRICAL CIRCUIT DIAGRAM Fusible link No.1 Ignition switch (IG1) Fusible link No.5 Fusible link No.3 Fusible link No.6 J/B (Fuse) No.40 7.5A No.42 15A J/B (Fuse) No.33 15A Stop lamp switch On On Off Off Hydraulic unit (HU) Electric power steering Solenoid valve Motor Stop lamp ABS-ECU Motor power supply Front wheel speed sensor (LH) Off Brake fluid On level switch Front wheel speed sensor (RH) Solenoid valve power supply Rear wheel speed sensor (LH) Rear wheel speed sensor (RH) Parking Off brake switch Motor power supply Engine-ECU <M/T> or Engine-A-M/T-ECU <Automated manual transmission> J/C (CAN2) On J/C (CAN1) Diagnosis connector Combination meter (ABS warning lamp and brake warning lamp) AC314136 AC 35B-6 FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS) CONSTRUCTION DESCRIPTION CONSTRUCTION DESCRIPTION SENSORS M2351001000234 WHEEL SPEED SENSORS AND MAGNETIC ENCODER FOR WHEEL SPEED DETECTION Rear Front Encoder for wheel speed detection Encoder for wheel speed detection AC311647 AC311648 Rear ABS sensor Front ABS sensor AC312272AB Wheel speed sensor is a kind of a pulse generator consisted of a magnetic encoder (a plate on which north and south pole sides of the magnets are arranged alternately) for wheel speed detection which rotates at the same speed of the wheels and a speed sensor (semiconductor sensor), and it outputs frequency pulse signals in proportion to wheel speed. Front wheel speed sensor consists of a front wheel speed sensor secured on the knuckle, and a magnetic encoder for wheel speed detection fitted to the inside of the front wheel bearing. Rear wheel speed sensor consists of a rear wheel speed sensor secured on the rear hub, and a magnetic encoder for wheel speed detection press fitted to the rear hub inner ring. ABS-ECU M2351003000218 • By integrating ABS-ECU into the hydraulic unit, no more wiring harnesses for sending signal that operates the solenoid valve and pump motor is required, assuring higher reliability. • Self-diagnostic programs and memory functions are integrated into ABS-ECU. If any malfunction is detected by the self-diagnostic function, ABS-ECU activates a fail-safe function and illuminates ABS warning lamp and brake warning lamp*. NOTE: *: ABS-ECU illuminates the brake warning lamp as EBD control warning lamp. • ABS-ECU detects vehicle speed from the wheel speed sensor signal, recognizes the wheel rotation, estimates the wheel slip condition based on the preprogrammed algorithm, and then controls the solenoid valve in the hydraulic unit so that the wheels do not lock. ABS FLUID PRESSURE CONTROL ABS CONTROL CYCLE The hydraulic unit is basically the same as that of the 2000 PAJERO PININ. FOUR-WHEEL CONTROL 4-wheel independent control Vehicle travelling Independent direction control Independent control Independent control Independent control AC208547AC ABS fluid pressure is controlled independently for four wheels. FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS) CONSTRUCTION DESCRIPTION 35B-7 EBD FLUID PRESSURE CONTROL EBD operating conceptual design Braking force distribution by EBD control Ideal distribution curve when seated by fixed persons Rear braking force Braking force distribution curve by the existing proportioning valve Ideal distribution curve when seated by one persons Braking Force Improved Front braking force AC208548AB EBD control is activated within the lower slip ratio area where ABS is disabled. EBD calculates vehicle deceleration and slip amount of the four wheels based on the wheel speed sensor signal. If the rear wheel speed differs from the vehicle speed by a certain level or more, EBD boost, holds, and depressurises the rear wheel control solenoid valve in the hydraulic unit, and then adjusts rear wheel brake fluid pressure fairly close to an ideal distribution curve. INITIAL CHECK ABS-ECU internally activates the self-diagnostic function. ABS-ECU illuminates ABS warning lamp for 3 seconds (including the initial check) * after the ignition switch is turned ON. If any malfunction is detected, ABS-ECU continues illuminating ABS warning lamp and disables ABS control. NOTE: *: ABS warning lamp may stay ON after the ignition switch is turned ON until the startup vehicle speed reaches approximately 10km/h. As far as ABS-ECU memorizes any diagnosis code related to the wheel speed sensor malfunction recorded during previous ignition ON status, ABS-ECU continues illuminating ABS warning lamp until it verifies that the malfunction for that code is resolved (Startup check). STARTUP CHECK When the startup vehicle speed reaches approximately 15km/h, ABS-ECU performs the following checks. 1. Motor, solenoid valve check (only in initial startup*) Operates the motor relay in ECU and checks the pump motor operation. At the same time, ABS-ECU sequentially energizes each solenoid valve in a very short period and checks the valve operation. NOTE: *: Initial startup indicates a first startup after the system has started. 2. Wheel speed sensor check ABS-ECU checks for any wheels that have not received ABS sensor signal from the startup. CONSTANT CHECK ABS-ECU constantly checks the following items. 1. ABS-ECU Performs self-diagnosis in ECU. 2. ECU power supply Checks if ECU power supply voltage reaches within the operational range. 3. Wheel speed sensor (1) Monitors the output voltage of the sensor signal wiring harness and checks for abnormal output voltage (open/short circuit). (2) Checks for any wheels that do not send pulse signal while the vehicle is in motion. (3) Checks if wheel speed which is abnormally higher or lower than the vehicle speed is input. 4. Pump motor and solenoid valve Checks that ABS-ECU output signal and the operating condition of the pump motor and solenoid valve agree with each other. FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS) 35B-8 CONSTRUCTION DESCRIPTION CAN COMMUNICATION FAIL - SAFE FUNCTION ABS-ECU outputs ABS warning lamp and EBD warning lamp* illumination request signals to the combination meter through CAN communication. NOTE: *: ABS-ECU illuminates the brake warning lamp as EBD control warning lamp. If any malfunction is detected by the self-diagnostic function, ABS-ECU illuminates ABS warning lamp and brake warning lamp*, and it controls ABS and EBD as shown in the following table. NOTE: *: ABS-ECU illuminates the brake warning lamp as EBD control warning lamp. Diagnosis code No. Item C1200 Open or short circuit in wheel speed sensor (FR) C1201 C1205 C1206 C1210 C1211 C1215 C1216 C1225 Action during fail-safe operation ABS control EBD control CAN output Brake warning lamp ABS warning lamp ABS disabled • Prohibited Two or less Output wheel permitted abnormal • Enabled Two or less wheel Abnormal: OFF Three or more wheels Abnormal: ON ON Open or short ABS disabled circuit in wheel • Prohibited speed sensor (RR) ABS enabled Wheel speed • Depressurise sensor (RR) s rear wheel system brake fluid pressure. Open or short Prohibits all circuit in wheel wheel speed sensor (RL) control after Wheel speed control is sensor (RL) system completed. Two or less Output wheel permitted abnormal • Enabled Two or less wheel Abnormal: OFF Three or more wheels Abnormal: ON ON Wheel speed System sensor malfunction shut-down System shut-down ON ON ABS enabled Wheel speed • Prohibits sensor (FR) system Three or control of more malfunctioni Open or short wheels ng wheel. circuit in wheel abnormal Prohibits all speed sensor (FL) • Prohibited wheel Wheel speed control after sensor (FL) system control is completed. Three or more wheels abnormal • Prohibited Output permitted FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS) 35B-9 CONSTRUCTION DESCRIPTION Diagnosis code No. Item Action during fail-safe operation C1226 Control solenoid Prohibited valve (FR) pressure holding system C1231 Control solenoid valve (FR) decompressing system C1236 Control solenoid valve (FL) pressure holding system C1241 Control solenoid valve (FL) pressure reducing system C1246 Control solenoid valve (RR) pressure holding system C1251 Control solenoid valve (RR) pressure reducing system C1256 Control solenoid valve (RL) pressure holding system C1261 Control solenoid valve (RL) decompressing system C1266 Motor system (stuck) C1273 Motor relay stuck off C1274 Motor relay stuck on C1276 ABS control EBD control CAN output Brake warning lamp ABS warning lamp Prohibited Output permitted ON ON Prohibited Enabled Back up mode Output permitted ON ON Valve relay system System shut-down System shut-down Output permitted ON ON C1278 Valve relay system stuck off System shut-down Control disabled Output permitted ON ON C1279 Valve relay system stuck on Control disabled Control enabled on valve relay system Output permitted OFF ON C1345 Brake fluid level failure Enabled Enabled Output permitted ON OFF FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS) 35B-10 CONSTRUCTION DESCRIPTION Diagnosis code No. Item C1398 C1607 Action during fail-safe operation EBD control CAN output Brake warning lamp ABS warning lamp Gas Test is running Prohibited Prohibited Output permitted ON ON Trouble in ABS-ECU Prohibited Prohibited Output permitted ON ON Trouble in ABS-ECU (CAN Initialization malfunction) Enabled Enabled Output impossible ON *1 ON *1 C1860 High voltage at ABS-ECU power supply (16.8V or more) Wait Wait Output permitted ON ON C1861*2 Low voltage at Wait ABS-ECU power supply (9.6V or less, 7.6V or more) Enabled Output permitted OFF ON Low voltage at ABS-ECU power supply (7.6V or more) Wait Output permitted ON ON Enabled Output prohibited ON *1 ON *1 U1073 ABS control Wait Trouble in CAN bus Enabled system NOTE: . • *1: If any trouble occurs in CAN communication, the brake warning lamp and ABS warning lamp on the combination meter turns ON. *2 • : DTCs are recorded only when the vehicle speed is 6km/h or more. • Prohibit: Any controls are not performed until the ignition switch is turned OFF. • Wait: ABS control is restarted when the normal condition is resumed even though the ignition switch is not turned OFF. DIAGNOSTIC FUNCTION • Actuator test DIAGNOSIS CODE SET There are 22 diagnostic items. Since all the diagnostic results are recorded in volatile memory (EEPROM*), they are stored in the memory even though the battery terminals are disconnected. NOTE: . • *EEPROM (Electrical Erasable &;Programmable ROM): Special type of memory that can be programmed or erased electrically • For each diagnostic item, refer to Fail-safe Function. SERVICE DATA OUTPUT ABS-ECU has the following functions for easier system checks. The following items can be diagnosed The following items of the ECU input data can be using the MUT-III. read using MUT-III. • Diagnosis code set The system is normal • Service data output Item No. Check items Check conditions Normal conditions 01 FR wheel speed sensor 02 FL wheel speed sensor 03 RR wheel speed sensor 04 RL wheel speed sensor Perform a test run of the vehicle. Speedometer display and MUT-III display almost agree with each other. FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS) 35B-11 CONSTRUCTION DESCRIPTION Item No. Check items Check conditions Normal conditions 05 Power supply voltage Always 10 V or more 06 Stop lamp switch The brake pedal is depressed ON The brake pedal is released. OFF ACTUATOR TEST Activation Pattern End of activation Start of activation Solenoid A valve B C 0.05 s On Pump motor Off 1s 2s 0.01 s Note A: Hydraulic pressure increases B: Hydraulic pressure holds C: Hydraulic pressure decreases NOTE: . • When ABS-ECU is disabled, the actuator test cannot be performed. • The actuator test can be performed only when the vehicle is stationary. When the vehicle speed reaches 10km/h, the forcible actuator operation is disabled. • During actuator test, the ABS warning lamp illuminates, and ABS control is prohibited. • Refer to Service Manual for actuator test specification. • ABS warning lamp continues illuminating until the communication between MUT-III and ABS-ECU is completed. Item No. Check item Drive Contents 01 Solenoid valve for front-right wheel 02 Solenoid valve for front-left wheel 03 Solenoid valve for rear-right wheel Solenoid valves and pump motor in the hydraulic unit (simple inspection mode) 04 Solenoid valve for rear-left wheel AC300188AB The MUT-III can be used to force-drive all solenoid valves and the pump motor.
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project