Front washer pump activates when headlight low/high beams are activated

Phillip Diagnostician Alaska Posted   Latest   Edited  
Resolved
Electrical
2011 Chevrolet Suburban 2500 LT 6.0L (G L96) 6-spd (6L90)
Front Washer Pump Activates When Low/High Beams Are Activated

So as the title says. NOTE: Front windshield washers. Vehicle does NOT have headlight washers. I started my diagnostics by monitoring the BCM PID's. When ever I activated low/high beams in any combination, the BCM does not see a request for the front washer pump. To me this indicates the short is not in the switch to BCM. So then I went to #7 15 amp fuse for the front washer pump located in the engine compartment. I remove the fuse and then activated the low/high beams. The pump did not turn on this time. This to me says the wiring from the fuse to washer pump is not shorted. I then gained access to the BCM and tripled checked my wiring to make sure I had the correct wires. I scoped washer pump relay control(ground controlled form BCM) at the BCM connector #X4 pin #15 orange wire. When I activated the low/high beams I did not have a short. At this point I called the fuse box located inside the engine bay. NOTE washer pump relay is a PCB mounted relay. It was installed and I got a call saying the problem still existed. At this point I was like impossible. So I went back and yes the problem was still there. I then retested everything and came to the same conclusion. I am tempted to have them get another one but I figured I'd ask for another set of eyes cause clearly I am not seeing something. I guess I could have a bad part but to me that is unlikely.

Edit. I just realized that ground G101 is a one way to the washer pump #7 15 amp fuse. IDK how I missed that but I will be checking that out tomorrow. Also I had checked all the connector under the fuse box no issues found. 

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Interesting
Mark Engineer
Colorado
Mark
 

It’s late here, didn’t look closely at wiring diagrams, is it possible this vehicle was in a fender bender and the body shop did something to a front harness?

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Phillip Diagnostician
Alaska
Phillip
 

I do know this was railroad truck and had some aftermarket stuff at one time. But I would think I would be seeing a short somewhere. I did do a visual inspection and didn't see anything jump out at me.

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David Mechanic
United Kingdom
David
 

Phillip you don’t say if the screen is operating normally. I presume it has headlight washers, could the pump wiring or the pipe work be mixed up ? just a thought, regards Dave T…

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Phillip Diagnostician
Alaska
Phillip
 

No the front windshield washer. No headlight washers.

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Steven Owner
Florida
Steven
 

possible bad ground (hunting) at G100

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Dmitriy Analyst
Ontario
Dmitriy
 

Edit. I just realized that ground G101 is a one way to the washer pump #7 15 amp fuse. I think you have answered the question. Is there a wiring diagram page that shows everything that sits on G101?

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Phillip Diagnostician
Alaska
Phillip Resolution
 

Yep the G101 ground wires were all broken off. Once I grounded them, the washer worked. I guess all i need was to type and and look at my diagram again then post it to realize where I made my mistake.

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