for some reason my dome light and the lights in the rearview mirror will not go out. I suspect a bad door switch can anyone tell me if the mirror lights come one with the dome when the door is opened ????[:@] thank for your advice John

 

If you don't have the dimmer all the way up, then it definitely sounds like a door switch. I believe that the doors work off of a switched ground (single wire) and actually complete the ground when the switch is out. You could pull the switches one at a time until the lights turn off. If by chance they work off of an interupted ground, then you'd have to ground the wire out of the switch to the chassis to check the switches.

 

Check your dimmer switch first. You wouldn't be the first person to trouble shoot dome lights on all the time. Took me almost an hour to figure out why the dome lights were staying on. Then I realized it had a switch on the rear dome light that we never saw before, however we must have flipped it while unloading the truck.

 

im having the same problem on my 88 i checked the soor switches and the are fine i replaced the dimmer and still nothing

 

On my blazer there "door open" pin switches on both doors, and also switches in the door handles. e.g., the lights come on if the doors are locked and you pull the inside or outside handles. Not sure why they did it this way at the factory, but it's convenient because you can wire up a warning chirp to the dome lights if you're adding an alarm system.

Anyway if you have the handle switches as well they could be culprits.

 

The lights activating with the door handles is a convience feature. The doom lights come on when you lift the handle so you can see inside your purse or find the right key on the key ring if your parked in a dark place at night. They took it a step further and put a conveince light in the outside mirrors.