Question about light wiring

[Elizabeth Henson]

So I'm having an issue with the lights in my 2005 GMC Sierra 1500. The dash lights, heated seat lights and even the headlights will flicker on and off. Sometimes if you hit a bump it will make them go off or come back on. Every once in a while the headlights will flip off and then right back on. But... the gauges work, the window, lock, and heated seat switches work even when the lights don't. The switches on the steering wheel work and the radio dials, heater switches on the dash... everything still works. The only things affected are the lights. You can push the dimmer dial and even right above the dimmer dial and the lights will come back on. And sometimes you can smack the dash and they'll come back on. Lots of info but I'm hoping someone can help me figure this out. Oh, and the service engine light never goes off even when the other things do. Any thoughts?? 

[richard wysong]

probably a bad light switch, but check the connector for any signs of over heating

[dna9656]

Sounds like loose wiring plugs or bad grounds. You can find where the grounds are located using the GM service manual; it may not be in the general one, it's prolly in an electrical systems book. It's prolly on line like most everything is. On my 06avalanche there are /is a grounding point under the driver's feet (not under the carpet) near the frame, it's a bolt with a few wires under it. Remove the bolt, wire brush the wire ends, make sure the metal under the bolt is clean, apply some die electric grease (sparingly) to the wire terminals to stop corrosion and re-install the wires and bolt. Check your issues. if fixed carry on, if not look for more bad grounds/loose plugs.

[Elizabeth Henson]

Richard Wysong, there was one time the dash got so hot it almost burned my finger. And I have noticed it seems to be worse when we use the heater. Do you know where I can find the connector or what the official name of the connector would be in case I need to find a diagram online?

[Elizabeth Henson]

Dna9656 thanks. I'll for sure give this tip a try. It can't hurt to clean it up. Electronic stuff is what confuses me the most. Also, I forgot to mention, the four wheel drive isn't working either. My husband thinks it may be in the switch and that it's related to the light problem.

[richard wysong]

the connector is on the back of the light switch. sounds like you may have some disconnected duct work for the heater behind the dash. scan tool may be able to help with 4wd problem