Horn & wipers went crazy!
 

So I was driving today. It was raining fairly hard and was really humid out (prolly close to 100%) anyways all of a sudden my horn started going off without me touching the button and my wipers started spraying fluid all by themselves and wouldn't quit. I pulled over and turned the truck off which made the wipers quit but the horn would not shut off so I just cut the power wire to it. Turned the truck back on and everything seemed back to normal... Any idea what happened? Was kinda scary considering it was already raining and the wiper fluid made it nearly impossible to see when I was going 45+...

Check fuses, then look for shorts. horn and wipers are keyed together in several places.

All fuses are ok. Any places in particular that you would suggest to check for a short?

nothing comes to mind, let me go get a diagram and check that out.

Sarcasm?

No, he probably has a wiring diagram. He works (or worked?) at a dealer

Check for evidence of water leakage into the Smart Junction Box under the passenger side kick panel. This seems to be a fairly common problem with the SJB trucks, 2004 and 2005 in particular.

Moved to a new place now. Tenneco Industries.


Diagram says they meet at SJB, like Bob says. there's a TSB for water leakage i believe.

You were right Bob and Alex. It's damp in there.

Use a hair dryer. Check wires for any corrosion. I can't think of a simple fix besides taking the windshield out and fixing it from the outside.

This was the first time it's happened and it's rained Way harder before. Might just have been a random thing. If it does it again I'll try and find the leak. Didn't see any corrosion though.

I had the same problem on my 05. I finally tracked it to the SJB and took the thing out of the pickup and took it apart.
There were 'salts' from water condensation all over the circuit board so I took a toothbrush to it after it had dried and cleaned it really well, then reinstalled everything under a plastic wrap for store bought water. If the salts get wet they will conduct electricity. That plastic is pretty tough and is very flexible.
I didn`t want to make it water tight because any condensation would not escape if it found its way into the SJB container say just after the A/C had been running. Anyway, I had no more problems. There is no way to take apart the circuit boards so you have to get a skinny bottle brush and gently go after the insides of the boards with that. Take the plastic and lay it on the back with enough left over to drape down the front. Looks like the SJB is pretty tough but I'm sure there is a limit on water.