rear wiper clunk when foglights go on first time..

[siume99]

I've been noticing sometimes when I turn on my foglights on, my rear wiper will "clunk," (like when it reseats itself after doing a single sweep).  The wiper doesn't go through its arc.  I only get this once in a trip (definition of trip is still being determined  currently I'd say its anything over 1 mile).  But, even then it doesn't do it everytime (especially if I have someone helping me diagnose the problem :angry:  ).  I can't limit the conditions it happens in either (sunny, raining, cold, hot, automatic/manual headlights on/off).  Has anyone heard of this?

[DallasZ71]

My tahoe does the same thing....its hard to duplicate

[SFPegasus]

When I was looking for a new switch for my Tahoe, I found out that the switch for the foglights comes in four syles:

 

1 - fog lamp switch with a blank below it (cargo door option)

2 - fog lamp switch with a cargo lamp switch (pickups)

3 - cargo lamp switch with a blank above it (pickups)

4 - fog lamp switch with the washer-wiper switch (liftgates)

 

It's impossible get a cargo light switch to fit in the space below my fog light switch.  You have to replace the whole damn assembly with a two-switch unit.

 

In your case, it's a single unite with two functions (fog lights, washer/wiper), as opposed to two separate modules.

 

The wiring diagram shows a lot of common circuits.  It wouldn't surprise me to find that there's some cross-wiring causing the relay to "jump" as you indicate.

[siume99]

Thanks Pegasus.  I didn't realize they were the same circuitry.  I just assumed that "two buttons" = "two circuits".  I could see some of the circuitry being the same if the buttons operated something in the same general area of the truck (backup aux lights and rear wiper).  I have the shop manuals, so that's one way to kill a few evenings.  If nothing else, I'll be forced to learn a little about reading circuits.