Rain Tracker RT-40A Troubleshooting Procedure
Motor Switching Applications
This procedure is for Rain Tracker installations that apply current directly to the wiper motor. For example, HSS (Hot Side
Switching) and GSS (Ground Side Switching) applications. If the installation required external resistors, see the “External
Component Applications” procedure.
Following this procedure will save you time.
1. Check Rain Tracker getting power and ground
Use a multi-meter or test lamp. Unplug the Rain Tracker interface (J1) so you can put the test probes into the connector.
Symptom
Check
12 V Present?
Go to step 2
No 12V
If possible, check the ground with a multi-meter. It should be no more than a couple ohms from
the Rain Tracker ground (black wire) to a good chassis ground. (Such as the connection outside
metal sleeve of the cigarette lighter.)
2. Check how the system behaves in each of the manual modes.
With the Rain Tracker activation switch off:
Symptom
Check
Manual off, slow, and
Go to step 3
fast and wash work as
before
Manual slow does not
Check the connections to the SLOW relay, both the motor and the switch side. (PPL and BLU
work
on the Rain Tracker.)
Wipers run all the time
Fast speed is slower than
it should be
Fast does not work
Wash does not work
If the system is responding to water but manual slow is not working, then the problem is
probably the SNC connection. (PPL wire from the Rain Tracker.)
Could be a damaged Rain Tracker interface module. See “Bypassing the Rain Tracker”, below.
There is some wiring error that is shorting the wiper motor slow and fast windings together. For
example, if the power diode (YEL & WHT) from Rain Tracker not wired in place. Be sure to
correct this, as it wears the wiper motor out.
You should not have cut or tied into any wire to control FAST... did you?
The Rain Tracker does not control wash. Did you cut a wire you should not have?
Bypassing the Rain Tracker
If you are still having trouble with the system in manual modes, try this diagnostic:
Remove the Rain Tracker interface module. Use a stiff wire to connect the BLU and PPL wires together at the Rain Tracker
interface connector. Connected this way, the wiper system should behave just as it did from the factory. If it does not, there
is come problem with the interface wiring.
3. Verify that the interface can make the wiper motor run—Pulse the Rain Tracker
activation switch.
With the ignition on, turn on the activation switch for a few seconds. Each time you do this, the wipers wipers should run
slow once.
Symptom
Check
Wipers run slow for
Go to step 4.
one wipe when you
Rain Tracker RT-40A Troubleshooting Procedure : Motor Switching Applications
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Last Revised: 08/01/08
pulse the switch
I cannot hear a relay
click inside the Rain
Tracker interface module
when I pulse the wiper
switch.
I can hear a relay click in
the interface module, but
the wipers do not run.
You probably have a problem with the power, ground, or activation switch.
Check to see that the activation switch is working: there should be about 12V at the activation
switch / mode reader (GRY wire) coming into the Rain Tracker.
Check the wiring around the SNO terminal, and the power diode (GRN, WHT, YEL wires from
the Rain Tracker.)
Check for this especially common problem: the Switch and Motor side connections to the Rain
Tracker are reversed. The PPL wire from the Rain Tracker should go to the switch side of the
break you made in the SLOW wire. The BLU wire from the Rain Tracker should go to the
motor side.
Check: for all of these sorts of application (motor-switching applications) the connections are
fairly heavy gage wire—18 AWG or thicker-- in the vehicle.. If you have connected the Rain
Tracker to to any thin wires in the vehicle, you probably have connected to a wrong wire.
Wipers stop on the
middle of the windshield.
Could you have connected to some wire other than SLOW?
• For Hot-Side Switching systems: check that the SLOW wire goes to +12V for manual slow
mode, ground for off mode.
• For Ground-Side Switching systems: check that the SLOW wire goes to 0 for manual slow
mode, +12V for off mode.
Check the SNC connection (PPL wire from the Rain Tracker). Be sure it is going to the switch
side, not the motor side.
You may need to use the CAM Feedback feature of the RT-50A. If this is the case, you need to
purchase the RT-50A.
The wiper fuse just blew!
Some applications will do this if you try to run both the Rain Tracker and the intermittent mode
simultaneously. Keep the factory system off when running the Rain Tracker.
If you use the Hot Side Switching Diagram for a Ground Side Switching system, or the other
way around, you will be shorting power to ground, causing the fuse to blow or breaker to trip.
4. Diagnosing Sensor problems.
•
If you skipped straight to this step, go back and systematically go through the procedure from the beginning, eliminating
more common problems.
• The sensor adjusts itself to the windshield when it powers up. To be sure that it has done this, turn the ignition off and
then on.
• Place the existing wiper switch in manual off, and activate the Rain Tracker system
• See how the system responds to a spray bottle or garden hose.
Symptom
Check
System does not respond Did you mount the sensor so that the double-stick tape wets out against the glass?
to water at all.
• The sensor will not see through the red release-liner tape—you must remove it, and actually
install the sensor using the procedure I the installation manual..
• You cannot just tape the sensor against the glass without mounting it.
• The tape must be fully ‘wetted out’ (appears black from outside the vehicle)—you cannot
lightly tack the sensor to the glass.
• Verify that there is 12V getting to the sensor. Do this by unplugging the sensor, putting
two small bits of wire (resistor leads are a good choice) into the the sensor cable, and
checking with a multi-meter.
Sensor responds barely at Is the sensor mounted too far in the shade band? From the mid 90's on, most US vehicles come
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all.
with infrared-absorbing shade bands. The Rain Tracker sensor can be mounted on the edge, but
not deeply within, the shade band.
Is the windshield an infrared reflective type? These are rare! On some Chevy venture vans,
1995-2001. You can see the yellowish coating ending near the edge of the windshield, and
usually built-in antennas. The windshield logo may read "Sun Gate"
Wipers keep wiping
without water
A few follow-up wipes are normal. These are to clear water that might have blown off the hood
but might have missed the sensor.
The Rain Tracker (as well as the rest of the wiper system) works better with good wiper blades.
Extremely worn wiper blades will cause the system to over-wipe. In such cases, replace the
blades.
The sensor will be fooled by vibration; if you tap on the sensor, it will run the wipers. Don’t tap
on the sensor. False wipes due to vibration / road bumps are almost always caused by an
unsecured sensor cable. Use a black cable tie to secure the sensor cable to the mirror mount.
On vehicles that wipe from the center out (e.g. recent Chrysler vans) having the sensor too
close to the edge of the wipe pattern will make the system wipe too much. Center-out wipers
are more prone to the wipers making more follow-up wipes; it is more important to keep the
blades clean.
If the vehicle engine is not running, the wipers can run so slowly as to cause the wiper blades to
fool the sensor. Try the test with the engine running.
Wipers never completely
stop wiping-- very long
intermittent
Rain Tracker does not
respond fast enough
Sensitivity too low
Follow up wiping can be excessive under conditions just about the freezing. These conditions
are rare, and the Rain Tracker still should not cause smearing.
If the wipers never completely stop, replace the wiper blades (they were due for it, weren't
they?). Clean the area just over the Rain Tracker sensor, and polish the glass with a soft cloth.
Check each of the conditions listed above.
Note that it is normal for the wipers to speed up and slow down over several seconds. Real rain
storms do not start or stop instantly. The Rain Tracker should respond appropriately to a real
rain storm. With a spray bottle demonstration, it will appear to respond too slowly.
Rain-X or car waxes can makes the sensor too insensitive. You can use Rain-X or any other
hydrophobic coating, but clean the area just over the Rain Tracker sensor, and polish the glass
with a soft cloth.
The sensitivity detects darkness and increases the sensitivity a little at night.
Be sure the Rain Tracker coupler installation is reasonably free of air bubbles. (No more than a
few, each a few mm in diameter. If you use our supplied anhydrous alcohol pad to install, you
will get a permanent, high-quality bond.)
Sensor appears to
actually slow down with
more water
Sensitivity too high
If the sensitivity is not to the driver's liking, you may adjust it. See the installation manual.
This can happen in installations with external resistors. (Usually not HSS or GSS applications!)
Check to make sure that the external component values are correct. This condition can be tricky
to diagnose because it looks like a sensor problem. Use an ohmmeter to check the value of the
external resistors.
If the sensitivity is not to the driver's liking, you may shift it up or down using the procedure
shown in the installation manual.
The sensitivity detects darkness and increases the sensitivity a little at night.
On vehicles that wipe from the center out (e.g. recent Chrysler vans) having the sensor too
close to the edge of the wipe pattern will make the system wipe too much.
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No amount of water will
make the system run fast
Responds to water, but
Fast speed is slower than
it should be
Sensor wipes for no
reason
This model of Rain Tracker does not automatically run the wipers at high speed.
There is probably some wiring error that is shorting the wiper motor slow and fast windings
together. For example, if the power diode (YEL & WHT) from Rain Tracker not wired in place.
Be sure to correct this, as it wears the wiper motor out.
False wipes should be rare.
Sometimes the Rain Tracker will see the first droplets of water before the driver notices.
Wipers wiper when I
drive over bumps
Wipers wipe when I tap
the sensor
Late First Wipe
On very hot, humid days, water can drip down from the air conditioning units of the vehicles
ahead. This can cause enough tiny drops to trigger the Rain Tracker. Also, there can simply be
tiny droplets of water in the air in extreme humidity—the Rain Tracker detects water droplets as
small as about two one-hundredths of an inch. Simply turn the Rain Tracker off under such
conditions.
Check to be sure that the sensor is securely snapped into the Rain Tracker coupler.
This can happen if the sensor cable has a long way to go to reach the headliner, and is not
secured. Solution: secure the sensor cable to the mirror mount base with a black cable tie.
Stop tapping the sensor. Properly installed, the sensor is immune to normal vehicle vibration.
As with all rain sensors (including those sold on new cars), there will be times when enough
water has hit the windshield that you would like the wiper to wipe, but none has yet hit the
sensor. These cases should be infrequent enough that they are easily ignored. The Rain Tracker
is better in this respect than most rain sensors in the new-car market.
Rain Tracker RT-40A Troubleshooting Procedure : Motor Switching Applications
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