interior lights / electrical problem

[teamjnz]

Houston we have a problem.. Our interior dome lights go on and off intermittently. The only consistency I have seen is when moving the driver power seat. The lights go on when the seat is being moved and back off when the power to the seat is released. Otherwise there is no consistency, they go on and off by themselves. Just the dome lights only, not the reader lights. The only way to control them is by turning on the dome override so they stay off.

 

It is possible I heard a switch or relay clicking when the lights go on and off. I am not fully remembering

 

1999 GMC Suburban

 

Help resolving this problem would be kindly appreciated.

 

Thanks Friends

teamjnz

[asilverblazer]

Something certainly isn't wired to code there. Without a clue here maybe the door signal (that triggers the lights when the door is open) is close to the power seat wires, and they have rubbed through allowing an arc.

 

Maybe you have other passengers...

[budhayes3]

Man, I remember reading about someone having the same problem about 6 months ago...wish I could remember what they came up with!

[teamjnz]

I am wondering if I am going to get a call someday soon with my wife calling me and letting me know that she and the kids stranded somewhere.

 

teamjnz

[JimG]

Best bet is to trace the +12V line to the dome light back to it's fuse and inspect the wires as you go. Something's feeding it 12V - I agree with asilverblazer's idea that wires have had the insulation abraded to the point were they're arcing. However, I'm not sure I'd suspect the door trigger first; my starting point would be the power wire to the light. Although all those wires (dome light/power seat/door trigger) are probably in the same wire harness going down the driver's side and up the B pillar (or is it D pillar?).

I guess as a temporary fix (until you find the problem) you could remove the dome lights and use flashlights at night to see in the vehicle. Not the best method but it would prevent a drained battery.

[71GMC_3/4T]

I'm not sure how they do it nowadays, but they used to run +12V to one leg of the lamp all the time and ran another wire to the door switches (and/or headlamp switch) to turn the light on. I think orange was hot (+12) and the white wire was the one that was pulled to ground to make the light come on. If you had the white wire short to ground, it would turn on the dome lamp. The usual place for this short was under the seat or under the sill plate trim by the door. It could also be under the headliner.

Unfortunately these days things are getting so complicated that I hate working on them. The dome light is controlled by a computer circuit (notice how they dim slowly rather than just shutting off?). So now your problem could be a bad switch, shorted wire, or a bad computer module. Gut feeling tells me it's probably the module, but not the module itself but a bad ground or power connection the module. Look around up under the dash for clusters of black wires that are grounded to the chassis via a screw. Loosen the screw, wiggle the terminals, and retighten the screw. Bad grounds are hard to find. Intermittants are a pain in the butt... I hope for your sake it doesn't leave your wife stranded somewhere.

[citydriver]

Check the switch on the rear doors, you may have wacked it with something while loading or unloading something.....just a thought

[teamjnz]

When I get the chance I will take apart some of the trim and look for the bad wire. Since the lights don't fade out I am going to rule out a module at this time.

 

Thanks for the great information. I will have to wait and see when the time comes to get into it and hope that it doesn't become overwhelming since I really don't know about electrical stuff.

 

teamjnz