late GMT400 interior lights wont shut off like a door is open.

1999 K1500 suburban interior lights will not shut off unless I unplug the fuse. Dome override button doesn't change anything witch is weird. Tried a different switch and no change. vehicle been sitting 4 years. Fixed lots of things and did lots of maintenance to get it back on the road. Runs and drives great! But now suddenly lights stay on.

When driving with lights on the chime screams at you even with light fuse out. so night driving is NO. Fuse no 3 controls the lights. Assuming it's not the switch at this point.

Either a shorted wire or bad door switch. Driver door is ruled out because I can leave the key in ignition ant it will scream till I close the door and it goes away. So it's in one of the other 5 doors?
Anyone els have something similar? Probably not related but alternator just died too.
Hoping someone else has some good ideas. I'm probably going to have to check all the switches tho.

I always had issues with the door jamb switches. With them sticking and then corroding both.

Door jamb switch or a grounded wire. I've seen the wire come off the door jamb switches and hit ground too.

I'll pull the switches and see what I can find wrong. Thanks!!

Interior lights should have a constant power orange wire running to them, and there is also a white ground wire (but its not grounded). The light sockets and housings must be isolated from ground, so they have small spacers to keep them from grounding to the body. Basically it's a light socket with white and orange wires running back to the dash area.

The door switches are all interconnected by white wires, and it should also run to the dash switch (at least on older trucks). When a door is open it grounds the white wire and the lights turn on. Simple circuit, but different than most other lights on the truck.

Did you try opening a door, one at a time, and pushing in that switch, see if lights go out? You also will be able to tell if it fell apart, as==no spring pressure.
Be aware most of those had a interior lamp control module, and it then takes 30-45 seconds for the lights to dim and go out.
Also, not sure on this, but I think some had a switch at the back, to turn on all interior lamps, may have been built into the rear topmost lamp.

I tried pushing in each door switch with key on to force them off so I didn't have to wait for timer. Still they stay on. However I just thought about when this started and I think it Started right after I swapped out center interior light. Maybe I should remove that first then go for doors.

YEP!

see if any other odd things happen to be in the circuit. Just had an issue on my 90 burb where the gauges all went dead and turning on the head lights the buzzer buzzed bc it thought the key was off even while running. truck would run and drive ok. but the gage/idle fuse would blow as soon as the key turned to ON. it turns out some random power feed also goes to the d@mn TCC solenoid on the transmission on that circuit and it had rubbed through and the wire was shorted to the bracket. sometimes it's those sorts of things that drive a person nuts because it isn't logical.

Check the sill plates. The wiring runs through there an if a screw caught the ground wire they would stay on. They also like to break at the B pillars right at the transition from the sill plate to the B pillar trim. Could be worn through but not broken yet an grounded to the floor.

Also since it's a suburban I assume it has the overhead console. If someone tried to ad the map lights to come on with the dome light switches that could cause it too. Those lights use the same power but have a dedicated ground so as to not turn on all the dome lights with the switch. You can ad them to come on with the door like the rest but you need a diode to do it.

Sounds like an unintended ground at a light housing may be the culprit. The switched ground for the lights can be confusing if someone is used to other circuits that switch the power side.

Removed dome light I changed and it's still the same. On to the doors. door switches have black and purple.

Found it. Removed and kinda cleaned rear switches and now they work good again? Weird

Oh and the dome fuse also controls charging system. That came back on with the fuse