UPDATE 8/7/2021: I'm no longer stumped, I solved the problem! See post #26 below for the solution.

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Hello everyone, I'm really stumped on this one and would appreciate your thoughts. I just bought an SRT6 roadster a few weeks ago and this forum has been invaluable in addressing a number of issues. This particular wiper issue was present when I bought the car.

I've read the other threads related to wiper malfunctions, and while some issues were similar to mine, I did not see a verified resolution.

My wipers come on with the key in the "on" position, regardless of the setting of the multifunction switch. They cycle about 7 or 8 times before stopping in random positions. This repeats whenever the multifunction switch is rotated to any position, including back to "off".

Following the procedure in the service manual, resolution is to replace the BCM. However... I am finding this difficult to believe since I have already replaced the BCM for at least one other issue. The wiper issue remained exactly the same before and after replacement with the "new" (used on eBay) BCM.

Not being satisfied with the answer, I did more troubleshooting steps. Summary:

• I unplugged the wiper motor, and plugged in a "new" (used on eBay) wiper motor. Same behavior.
• With no wiper motor plugged in, I measured the voltage at pin 1 of the BCM. Voltage was ~12V for roughly the same amount of the time it took for the 7-8 cycles, then went to zero, consistent with the behavior of the wipers when plugged in.
• I measured the voltage at socket 65 of the wiring harness (not plugged in to the BCM). Verified proper operation of the multifunction switch (voltage at zero when multifunction switch is turned off, and ~+12V at any of the other positions (Int, Low, High).
• I replaced the wiring harness to the BCM, but removed the embedded C3 connector (so no voltage from the multifunction switch would be present at pin 65 of the BCM). The wipers still behaved in the same way (voltage present on pin 1 for a short time before returning to zero).

Thanks in advance for any help you may be able to provide.

 

Pin 1 of which connector? Pin 1 of C2 (as well as pin 2 of C2) should be HIGH along with pin 41 anytime the key is "ON". When you turn the wipers "on" one or both of pins 1 and 2 should go low, that is how I read the diagram. Those are switched grounds.

My first thougth was you have a bad "park" switch in the wiper motor, but since you changed it and it still did it, I'd say that's not the cause. YOu have proven the MF switch is OK.
I cannot think of any other function of the BCM that would activate the wiper motor.

Here is a question for YOU: How do you read the diagram? Does the motor's park switch MAKE or BREAK the connection from pins 41 and 40 when the wipers reach the 'Park' position?
Do you see any change of state on pin 40 that coincides with the wipers turning off?

This is an odd one.

 

I like PizzaGuy's idea of the 'park' switch being the issue, reminded me of friend's old porsche with same issue.
He threw a lot of money replacing everything, no change.
Someone told him the switch wasn't grounded and to put a ground from the wiper motor to chasis. It worked perfectly.
OP did say motor was replaced and same problem, grounding may be an issue?
I found this article of interest:
https://www.rockauto.com/genImages/1...erProblems.pdf

Worth a try.

 

Yea, but ours does not work that way, no ground is needed at the motor, the BCM switches ground to the motor to operate it.
The Park switch in the motor has one pole to 12 volts, the other pole goes to the PARK input on the BCM.

As is so often the case, our cars are not set up like 'normal' cars....

 

Hi pizzaguy, thanks for your questions. Here's what I know:

1. I measured ~12V between Pin 1 of the BCM (corresponding to Pin 1 of C2) and Pin 41 of the BCM (corresponding to Pin 41 of C2) when turning the ignition switch to "on", irrespective of the MF switch position (off, int, low, high). I had thought it was positive voltage (i.e. Pin 1 at the higher potential), but given your question ("How do you read the diagram?") I'm no longer sure and would have to check again. Voltage goes to zero after roughly the same amount of the time it took for the 7-8 cycles.
   • In retrospect, I should have measured the voltage at each pin with respect to chassis ground. In either event, there is clearly a voltage differential between Pins 1 and 41 that is driving the motor whenever the ignition switch is turned to "on", irrespective of the MF switch position (off, int, low, high).
2. I did check the park switch operation in the wiper motor. As expected, with the wipers parked, there is ~0 ohms resistance between C2 sockets 40 and 41 (MAKE). In all other positions this is an open circuit (BREAK)
3. I did some poking around with my new Micropod 2. This is still new to me, but believe I learned the following today:
   • BCM module is functional with no DTCs and appears to be operating as expected.
   • The BCM Input/Output functions showed correct operation of the MF switch (see picture below; correct indicators (on/off) were read with the corresponding position on the MF switch).
   • The BCM Input/Output functions showed correct indication of "WIPER MOTOR STUCK" (i.e. it was "NOT ACTIVE" when the wipers were in motion, and "ACTIVE" whenever the wipers stopped).
   • The WIPER CKT GROUND function always read "NOT ACTIVE", regardless of wiper operation. I don't know what this means.

Back to your question - "How do you read the diagram?" - at first I thought that pin 41 would be at ground potential, despite the words in the diagram, because the service manual prescribed applying B+ to Pin 1 and ground to Pin 47 to test the operation/function of the motor. Also, the harness wiring color is Red for Pin 1 and Black for Pin 47. However, if you take the words literally in the diagram, your interpretation makes much more sense (Pin 41 is HIGH, and the low/high speed controls are switched grounds. At park, +12V would be applied to the "Wiper Park Switch Sense" (pin 40) to signal the control circuitry to switch either Pin 1 or Pin 2 HIGH to shut off the motor).

Which leaves the remaining question: With no voltage present at Pin 65 at ignition "on", why is there a voltage differential between Pins 1 and 41, driving the motor at all?

 

Thanks, forgot....'electronics'
Life was easier, less complicated.

 

I would tend to think that the multifunction switch was bad. It has often failed for many reasons in the past, would it be possible to disconnect the MF switch and mimic it with powered jumpers?
Used ones are not cheap and not so easy for some to replace.
If you take the MF switch apart, that’s if it is possible, the park contacts may be burnt out. Is it always the same number of cycles?
If it does not park correctly then there is always power to operate the wipers, the park switch is operated every cycle but is over ridden by another switch which has power or no power as dictated by the MF switch.
I looked at the insides of a wiper motor once years ago and the park or continue to cycle mechanism was so simple, it was the subject of a lawsuit that went on for ages, the inventor won millions back in the sixties.

 

Hi onehundred80, I would have suspected the MF switch as well but it doesn't seem to be the culprit. With the MF switch entirely removed from the BCM harness (C3 connector physically removed), the wipers still operate. If the wiper function worked as designed then 0 volts (open circuit) at Pin 65 of the BCM should result in the wipers being (remaining) off.

 

There is a direct line of power fed from the fuse box, possibly the MF switch controls the cycles of the wiper motor by changing circuits in the BCM, the motor gets its instructions from the BCM.

 

As I read thru the thread, and particularly the last few posts - Im beginning to think that we are about to discover a mistake in the service manual.
There IS one thing tho, the BCM is in charge here, it is triggered by the output of the Multifunction switch, but it takes it from there.

I do not know how sophisticated or complicated the wiper function of the BCM is, but as I read thru this, I am starting to think the BCM is flaky.

 

If the BCM is flaky, he could try the old one he had if he still has it.
Newer BCM, newer motor, so why not try a newer MF switch?

 

two simple things to check the bcm needs to be install all the way down and back to make all connections do that try it again,,, change the rcm again make sure all pins are out Not pushed back,, these two thing can cause the wipers to turn on for 3 or 4 wipes when car is started. jim

 

Hi everyone - appreciate the help and feedback. Since my last post, I did some more troubleshooting, and replaced the BCM again (now on third unit). The issue remains and I don't have a clue where to go from here. Would greatly appreciate any pointers.

To recap, and referencing the diagram Pizzaguy provided, here is what I have done with all components related to wiper operation.

1. Power distribution and MF switch: Fuse 32 is intact and provides power to MF switch. (All fuses in fuse block are intact.). MF switch correctly controls wash functions as designed, wipe function exhibits issue. With MF disconnected from BCM, the correct voltages are present at BCM C3 socket 65 (0V when MF switch "off", ~+12V in INT/LOW/HIGH positions). MF switch operation was also verified with MF connected back to BCM (using DRB III emulator for BCM Input/Output functions).
2. BCM: this unit was replaced three times with similar (dysfunctional) operation of wipers. When the MF switch is not connected to BCM (i.e. removed C3 connector from BCM with all other connectors connected), the wipers still come on.
3. Wiper motor: verified similar (dysfunctional) operation of a second wiper motor. Following Steve1189's suggestion, I ensured the second wiper motor was well grounded, to no effect. Park switch operation works properly (i.e. when parked pin 40 of wiper motor is ~0 Ohms to pin 41 and to case ground, open otherwise.)
4. Wiring: Pizzaguy - I verified that pin 1 of the BCM provides ~+12V with respect to chassis ground (for the period of time that the wipers take the 7-8 cycles), and that pin 41 of the BCM is consistently at ground potential. I also verified that pin 41 of the wiper motor has ~0 Ohms to case ground. Pin 40 of the BCM is at +12V. (Suspect that when the wipers are parked, pin 40 from the BCM becomes grounded and completes the "sensing" circuit internal to the BCM.)
5. Grounding: I checked the ground connection at C4 socket 42 to the BCM, it is fine.

Utterly perplexed. At this point I would deeply appreciate anyone verifying voltages at pins 1, 2, 40, and 41 of the BCM (wiper motor unplugged) at all positions of the MF switch.

 

I did ask u to call Matt 786 877 5959 well text him he will return the call , he can fix the car spoke to him last week he has had the same problem in 5 to 6 mercedes and crossfires solved all of them jim

 

Thanks amx1397, yes I will call Matt sometime tomorrow.

 

One other item. The voltage at C2 pin 2 on the BCM stays at ~+12V for the amount of time it takes for the 7-8 cycles, then goes to zero. I can hear a relay click when it goes to zero. The BCM has a couple of relays on board, so this must be one of them... but since I don't know how the BCM works this really doesn't seem to give me any other clues.

 

Could this be triggered by the windshield washer/wiper circuit somehow?
Does the WW tank have any fluid in it, if not it may have been pumped dry before you saw the car.
The wipers and wash operate immediately with the MF switch end button pushed in and the ignition turned to the first position.
If the tank is empty put some fluid in it and see what happens.
I know that I am grasping at straws here.

 

UPDATE: I am still struggling with this issue. I would love to take this car to someone who knows (and is willing to work on) the body-related issues, but have completely struck out with finding anyone near me in Central Florida who can help.

I've attached a summary of the issue and what I have done so far to troubleshoot. If any of you are willing to give this a second (or first) look, you don't have to pour over the thread, just read the attachment. I will be eternally grateful to anyone out there who can help me.

 

You can try the forum member DualSportDad https://www.crossfireforum.org/forum...lsportdad.html he lives in Ft Myers and is a former Crossfire tech from the dealership.

 

Thanks, I have reached out to him. He is not able to work on cars at his home presently, but will be moving in September to a new home where I believe he will be able to work on cars again. He is also willing to travel, but I live in a condo where I am also restricted to work on cars here. In the meantime I sent him this data a few weeks ago... haven't heard back but I believe he is probably busy with his house move.