I had no 4 wheel drive, window wipers, or defrosters?

GERI WILSON

MEMBER
2000 CHEVROLET SILVERADO
V8
4WD
AUTOMATIC
150,000 MILES

Had the 2000 silverado in to the shop because I had no 4 wheel drive, window wipers, or defrosters. They changed a relay and said if it did it again it would need a new ignition switch or harness. I changed the harness and the relay under the hood for ignition. Still no 4 wheel or defrosters or wipers. Am I changing the wrong relay? The wiring harness was a mess. Someone had been into it before I got it and patched and spliced everywhere. It starts and runs good but no 4 wheel etc.

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

If someone was already messing with the harness and you replaced it, I suspect we have another wiring issue as well. Basically, these systems are not related and the 4WD system does not include a relay, so I suspect this is a relay that is for the PCM or other system. I am just not sure which relay they are referring to.

I am attaching the wiring diagrams for the wiper and 4WD system to illustrate this.

What we need to do is check voltage on the wiper system and 4WD system and track each issue.

https://www.2carpros.com/articles/how-to-check-wiring

It is unlikely that they are related but in the event, they are, pick one system and figure out what is going on with it and if that fixes all of them then that is a bonus. If not, then we need to move onto the next one.

Let me know what you find with this, and we can go from there.

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