When I press the horn,full beam comes on

[Dariusz Salomon]

99 Tahoe Z71. Hi all-recently noticed problem. When it's damp or raining(not everytime tho), when my lights are on,something's shorting and:
-right indicator doesn't work(front)
-horn doesn't work,but it turns full beam on
After about ten minutes of driving everything goes back to normal.
Only hapens with dipped beam on-not happening with sightlighs on or with lights off-so I assume the problem may lay in the headlight harness/headlight itself-right one,as only this side indicator doesn't work when it happens.
Where would you look first? If anyone had similar experiance please speak. Thanks for all suggestions.

 

[HotWheelsBurban]

I've not had a lot of experience with this sort of thing, but it sounds like a ground or a hot wire hitting somewhere and making everything crazy. Since GM decided in their wisdom to put so much of the lighting through the multi function switch on the column, I would start looking there. One of the problems with this setup, especially on a vehicle with a tilt steering column, is there are so many flex points in the wiring and linkage, that have moved around way more than anyone figured they would, in the life of the vehicles. GM most likely never imagined these trucks would last this long! As long as it gets past the warranty expiration, that's all that it's engineered/designed for....
We've had several vehicles that the MFS went bad on, and they all did different cuckoo things. On my Dodge Intrepid, the emergency flashers came on , just going down the road, and the only way to turn them off was to disconnect the battery! And this was a "brand new" switch! Fortunately on that car, pulling the steering wheel was not required to change the switch. Just unbolt the column cover, unbolt the switch, replace the parts. 15 minutes, two screwdrivers. Fixed it in the parts store parking lot!
I'd wager that the problem is either the switch (especially if it's the original one!) or the wiring harness is pinched somewhere.

 

[Dariusz Salomon]

I've not had a lot of experience with this sort of thing, but it sounds like a ground or a hot wire hitting somewhere and making everything crazy. Since GM decided in their wisdom to put so much of the lighting through the multi function switch on the column, I would start looking there. One of the problems with this setup, especially on a vehicle with a tilt steering column, is there are so many flex points in the wiring and linkage, that have moved around way more than anyone figured they would, in the life of the vehicles. GM most likely never imagined these trucks would last this long! As long as it gets past the warranty expiration, that's all that it's engineered/designed for....
We've had several vehicles that the MFS went bad on, and they all did different cuckoo things. On my Dodge Intrepid, the emergency flashers came on , just going down the road, and the only way to turn them off was to disconnect the battery! And this was a "brand new" switch! Fortunately on that car, pulling the steering wheel was not required to change the switch. Just unbolt the column cover, unbolt the switch, replace the parts. 15 minutes, two screwdrivers. Fixed it in the parts store parking lot!
I'd wager that the problem is either the switch (especially if it's the original one!) or the wiring harness is pinched somewhere.

As much as I figured so far, I believe it's "stealing" the ground from some other stuff-I will look into it once it gets warmer and dryer(damn winter lasts forever) beggining with lightbulbs connection and fuses,then I move on. I just thpught maybe someone had similar experiance-I wouldn't have to shoot in the dark.

 

[618 Syndicate]

It's the switch.
It's ALWAYS the switch...

 

[Dariusz Salomon]

It's the switch.
It's ALWAYS the switch...

Please,tell me it's not the switch....

 

[351FUN]

Oh yeah that's a ground. Anytime symptoms can be described as "really weird ****" it's a ground. I had one once on a the blazer that all dash indicators worked backwards (high beam light on with lows, turn signal indicators on when the bulb was off, etc) the needles acting crazy and some other symptoms I can't remember. It was the little ground wire under the dash.

 

[Dariusz Salomon]

And the fact that it seem to happen when wet (she sits on the drive face up on the incline)? Does it narrow it down a bit?

 

[Onizukachan]

Mine has a glitch where the spayers wont work. Some PO added in a ground from the wiper motor harness to body ground, and that resolved it… but also means whenever it gets wet the wipers turn on. I’d be looking in that area or the fuse box if you don’t have a cover.

 

[Onizukachan]

Or isn’t there a plug from column harness thru the firewall that might be getting wet and providing a path between pins perhaps?

 

[Dariusz Salomon]

Or isn’t there a plug from column harness thru the firewall that might be getting wet and providing a path between pins perhaps?

I'll look into it-I have a cover on fuse box.