Dome lights have a mind of their own

[elleehswon]

Long time lurker, first time poster.

So, I have a 2017 Tahoe LT and she has a weird electrical quirk. Sometimes, when I'm driving(dome/door lights switch can be either door controlled or off), the dome lights will come on, on their own , and maybe they stay on, maybe they flicker and go back off. Sometimes this is conjunction with going down or uphill, sometimes going over a bump, and sometimes just on a flat road while driving. If I try and fiddle with the overhead lights switch, there is no change in state of the lights. They'll stay on, even if the switch dusctstes they should be off.

Any thoughts on where I can start to troubleshoot this or have a circuit diagram from the lights on back? My first thought was a rollover sensor or something centric to the BCM. One of the mechanics at CarMax(bought the girl used) was able to get the lights to flicker by juggling some wires in under the dash, but wasn't able to replicate the problem after that. Any help would be greatly appreciated.

-mike

 

[OR VietVet]

Welcome to the forum from Oregon.

Sure sounds like a loose ground wire somewhere.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I agree with @OR VietVet that your symptom seems like a loose ground wire.

I would start with a replacement dome light bulb, just to be sure that the bulb/filament itself is not an issue. If the bulb itself is not an issue, I'd remove the bulb and attach alligator clips to the two electrodes in the dome light housing and connect them to a volt meter. Then drive around and see if you get voltage fluctuations (going to 0 volts). If you see voltage fluctuations, then it is time to obtain a wiring schematic for that circuit and trace back to the next connection point (perhaps under the dash like you mentioned).

 

[elleehswon]

ty for the welcome! so , there's the girl. she's pretty pristine. so, to expand a bit, the car has the dvd system behind the sunroof, but it's all the door lights. am i correct to assume that, if it's a ground wire, that the power is always run to the lights and the ground opens and closes the circuit?

 

[Joseph Garcia]

ty for the welcome! so , there's the girl. she's pretty pristine. so, to expand a bit, the car has the dvd system behind the sunroof, but it's all the door lights. am i correct to assume that, if it's a ground wire, that the power is always run to the lights and the ground opens and closes the circuit?

I would think that the power wire is the one that gets turned on and off. The ground wire should be firmly connected to a clean and tight ground connection somewhere on the truck.

 

[elleehswon]

so, this is more of "the lights come on when they shouldn't" than they go off when they shouldn't.

dome light switch is set to "off" result: lights sometimes come on, and flicker or stay on for some duration of time, sometimes a few seconds, sometimes many minutes
dome light switch is set to "door" result: lights sometimes come on, and flicker or stay on for some duration of time, sometimes a few seconds, sometimes many minutes
dome light switch is set to "on" result: lights stay on, no flickering, no nothing.

if the dome lights turned on, on their own and i do the following:

dome light switch is set to "off" result: lights stay on
dome light switch is set to "door" result: lights stay on
dome light switch is set to "on" result: lights stay on

 

[elleehswon]

So, as an update, the dome lights were replaced in their entirety and the problem persists. next up is to replace the BCM as only the BCM and the switch can turn the dome lights on, and , as the switch was off at the time, the bcm had to have been providing power. will fill you all in after monday when the bcm gets installed and programmed.