Rear washer motor stuck on

Have any of you Chrysler techs ever seen a failure mode where the rear
window washer comes on by itself and stays on? I traced mine back to
the fact that pin 50 on the BCM connector is staying grounded all of the
time. The part I don't know how to troubleshoot is the interaction with
the climate control subsystem in the console. Is there any way to know
if it has failed and is somehow commanding the BCM to run the rear
washer? Or is it more likely that the BCM pin 50 driver has failed
shorted to ground?

One interesting thing is that when the motor first failed on, even
shutting down the engine wouldn't stop it. I had to unplug the pump
connector to kill it. I then had a local garage look at it and they
couldn't find the problem, but said they thought the pump was bad as it
didn't run when they plugged it back in (it had been several months
since the failure). That was a couple of months ago and today it all of
the sudden came on again. The difference is that this time when I shut
off the engine, it would quit. I'm certain before it ran even with the
engine off, which seems hard to believe looking at the way the system is
wired (unless the ignition switch is also faulty and letting power
through it in the off position).

In addition, my front washer quit working recently. I haven't had time
yet to work on that, but was reviewing the manual this evening. I'll
check the washer motor itself first, but assuming that is OK, how hard
is it to get to the multi-function switch connector to check the washer
switch itself? The FSM diagram just shows it being on the steering
column, but isn't really clear how to get at it. I assume this
procedure is somewhere else in the manual, but I haven't yet found that
section.


Matt

 

Well, I tried my magic 8 ball but it wouldn't tell me what you were driving.

Since it kept going even after shutting down the engine, I think I'd find out
how the motor was supplied with voltage when the ignition switch was off before
I concerned myself with the BCM's interaction with the universe and various
subsystems.

 

Some of the older Caravans had this problem and the switch was at fault, but
since we have no idea what we are working on I cant be much help to you.

Glenn Beasley
Chrysler Tech

 

I hate it when that happens. My bad, 1996 Plymouth Grand Voyager, 3.3L,
4sp auto, AC, power windows and door locks, rear heat/AC.

Matt

 

Yes, my obvious oversight. 1996 Grand Voyager, 3.3L, 4 speed, more
details just posted in another post.

Matt

 

Ok, I mentioned earlier that the above applies to a 96 Grand Voyager.
This weekend I checked the circuit diagrams carefully (page 8W-53-3
through -6) and verified that both washer motors function and the
multifunction switch washer switch works fine.

I'm fairly certain that the rear washer staying on is due to a failure
in the BCM driver for pin 50, rear washer motor control. However, I
can't be 100% sure as I'm not sure how to verify that the AC/heater
control module is erroneously telling the BCM to run the rear washer.
Is there a good way to check this?

I'm less sure about the front washer not working. The diagrams on -3
and -4 suggest that the washer switch itself provides the ground path
for the front motor via circuit V10 to the switch and then Z1 to G200.
However, it appears to be paralleled to pin 19 on the BCM which is
called the front washer motor control, thus analogous to the rear washer
motor control. I assumed this was so that the BCM could sense the
washer switch being closed and thus run the wipers for the "wipe after
wash" feature. However, it seems in that case they would call it "front
washer motor sense", rather than "control." Anyone know for sure how
this works? I'm suspecting the BCM for the front washer as well, but
the circuit diagram seems to indicate that it doesn't play a role in
operating the front washer motor.

Matt