Interior lights flickering

I have a 1998 two-door Tahoe with an issue with the interior lights. I need some help in diagnosing this.

When it's hot outside and inside, the interior lights will rapidly flicker when turning right. Once the cabin cools down, it's fine.

When this happens, I can hear a switch clicking roughly above the brake pedal. I believe this is the "Interior Lighting Module".

I have replaced both door pin switches and the rear tailgate switch twice, the second time with ACDelco units. I have replaced the dash headlight switch and, for another issue, the multifunction (turn signal) switch which includes the headlamp dimmer (high-low beam) switch.

Looking at the wiring diagrams, it looks like the interior lights are fed from circuit 40 and are always hot. They turn on by being either grounded through the dash headlight switch (the interior light rotary dial) to ground #200 or through the Lighting Module which is seeing the door pin switches. Ground #200 is clean and tight.

It looks like the module gets a signal from the door pin switches, the module switch closes to ground circuit 156 and the interior lights turn on.

Diagrams are below. I'm leaning toward a bad switch in the module, but didn't want to throw parts at this. I've tried jostling the wiring at the module around but couldn't duplicate the problem. I don't know what else it could be. Any suggestions?

Does it have the barn doors or hatch? I have the hatch, and mine does it when I hit bumps. Drives me nuts.

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Thanks for the suggestion. It has the hatch (tailgate). The switch back there is new and the hatch doesn't seem loose.

It only does it turning right when it's hot in the cab. Once the a/c cools it down, it stops.


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I've got a '95 Yukon GT with the exact same symptoms as yours, even down to the right-hand turn.

Mine has barn doors, not a hatch, and I'm sure that the connection back there is solid, same with the doors.

This is almost guaranteed to be a grounding issue, I had a very similar problem with an Avalanche I used to own, turned out the culprit was a 1/4" grounding lug behind the dash that came loose. I haven't started digging around yet, but will let you know if I find anything.

For the time being the best solution I have is to just hit the DOME INTERIOR button so the flickering stops. That works on mine least.

Yeah, that's what I've done with mine. Since it's cooler, though, it doesn't seem to happen as much.

Thanks for the suggestion on the ground. It's worth looking into.

The module grounds at G202 which is in a ridiculous location (of course)...




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That's looking forward under the passenger dash, correct?

Just noticed you're in Jackson. I've got timber property down in Lincoln county, small world.

Yeah it is, I've been down that way many times.

Yes, that's looking forward (note the arrow) at the hvac box under under the passenger side. It looks like you'd have to roll the dash forward to get to it.


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My automatic interior lighting system is working correctly, if you need something checked for grounding or wiring or any kind of mulitmeter reading let me know. Doing right hand turns would make me assume its the drivers door not sealing properly, as it pulls away from the switch. Try pushing and pulling on doors to see if you can get it to do it.