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This is an odd one. We have an 08 police model, 3.9L, with about 113,000 miles on it. Every now and then the windshield washer pump activates by itself, without the wipers coming on. It seems to happen only when the air conditioning is ON. It will shut off after shutting off the AC, but it takes a while. Any else ever have this happen? Any ideas out there?
 

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That is very odd for sure.
I'm wondering if the mfs on the signal handle is not malfunctioning and the AC variable is coincidence ?
Can't really think of any connection between the 2 systems.

But

I been wrong before. I seen it happen.
 

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Strange problem for sure. I wonder if this is related to some type of Aftermarket Add on Gone Wild. Seeing there is no common link between the 2 systems. For Wiper they is a connection to the BCM. The HVAC has its own controls Modules for both Auto and Man modes and only 1 connection to the ECM. So in my mind it is a strange problem for sure. As stated before I wonder if it isn't just a coincidence to the issue...

In my mind there are some things that are strange with the problem. Once you start it by switch it would turn the wipers on by design. In Theory if it was a Bad Multi Switch it would turn on the wipers as well. I would think. I would then check grounds and make sure they are good, However I am not sure that is going to do anything as I don't know how it would be related to turn on the washer part with out wiper.

I don't want to say that it is going to be a BCM issue, However from what I can think of without a Short to the sytem, This could be underhood short around washer motor and wiring for it. Also could be from fuse box to washer motor, BCM to washer motor. Without a Short only thing I could think of would be a fault in the BCM

James
 

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This is an odd one. We have an 08 police model, 3.9L, with about 113,000 miles on it. Every now and then the windshield washer pump activates by itself, without the wipers coming on. It seems to happen only when the air conditioning is ON. It will shut off after shutting off the AC, but it takes a while. Any else ever have this happen? Any ideas out there?
I'm stumped, too.

My first thought was the control stalk for the wipers, turn signals and cruise control. If the stalk is failing, that could cause phantom operation of the windshield washer/wipers. But I don't see how it could be linked to the AC controls. I'm thinking maybe the behavior is just a coincidence.

About the only thing that might be connected is a ground connection going bad. That is, if somehow the AC controls and the stalk share a ground connection somewhere under the dash, and that ground is perhaps corroded and causing a voltage drop, maybe that's making the windshield washer come on.

The only drawings I can access are the EBSCO Host data. I couldn't find anything that indicated police car (or 9C1), so I chose the 3.9L LT drawings to look at.

It appears all the windshield wiper connections in the stalk go to the BCM - none of those signals go directly to the wipers. The BCM has separate wires going to the wiper motor.

I do see a common ground on the BCM, stalk and AC controls - G202. The drawing for ground distribution shows 13 things tied to G202 - most in the dash, but some under the hood such as the brake fluid level sensor.

Pins 1 and 5 on connector X3 of the BCM go to G202. So if you can trace those wires to a hard ground point, inspect it for corrosion.

On the turn signal stalk, pins E and H on X1, and pin D on X2, all come together at J214, which then goes to G202.

On the AC controls, pin 3 on X1 goes to G202.

If it really is a bad ground, that's where to look. But my instinct is that, if the BCM has a bad ground, there would be all sorts of other things going haywire.

So I'd focus on the pink wire (pin J of X3) out of the stalk going to pin 24 of X1 on the BCM. Maybe it's loose. Or maybe the washer switch in the stalk is going bad causing the the bad behavior. Or maybe there's a bad spot on the pink which intermittently is shorting (to ground) causing the washers to come on.

Anyway, without getting hands on, that's about as close as I can get to pin-pointing your problem :)

Doug

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