ive had this problem since i got the truck but its starting to bother me a little. but when i open the doors none of the courtesy lights come on.but they do work if i use the dome overfire button or whenn i unlock the doors using my keyless.. at night i have to hit the unlock button on my keyless to get the lights to come on so i can see getting in and out of my truck at night. is there a fuse to check or something?

 

Sounds like your door jamb switches are not working. Do they turn on when any of the doors are opened?

 

Nope doesn't work with any doors

 

What are you workin' on? Please post the year of your vehicle at a minimum and consider either putting your vehicle information in your signature (and check the check box to include it with each of your posts) or creating a garage which will put your vehicle information under your username.

 

Is the dome overide button pressed in?

 

HMMM! I suspect a short-usually leading from the B pillar to the drivers door-seen this twice-especially on north country units:corrosion! Shorts may be in the jamb switches or in related harness.

 

Let's clarify a few things just to avoid confusion:

A 'Short' means a short circuit. That results from wires crossing and touching each other or ground.. usually resulting in things being on when they shouldnt be, or blowing fuses.

An open circuit is when things DONT work when they should due to broken wire, bad connection or dirty corroded contacts.
You most likely have an 'open' circuit

And the pillar we are talking about is the A pillar. They are counted front to back.

GM did have a serious problem in the A pillar through-hole chafing wires in that passage hole. They countered it with a huge plastic donut in the flexboot sometime in the early '00s. My brother had a problem with the courtesy lights in his '05 pickup and I did a wiggle test in the harness between the pillar and the IP fuse panel. It started working and I couldnt make it fail again, before I found the problem. I suspected a loose connection in the fuseblock connector.

It failed again later and rather than let me find the culprit he traded the truck in.

I am not saying this is YOUR problem... IIRC, his mirrors and door locks didnt work correctly either.

For some reason I cant find the diagram containing the actual door switches and their destination connections.

To start.. check for 12 volts at the switch {they are on the 'grounding side'} ie, the switches work by grounding the courtesy lights. Since the body module turns them on, that rules out the 12v supply side and the fuse.

 

Sorry its a 2001 blazer 4x4.
The dome override is pushed in but when its pushed out the lights come on and stay on..
And where should a check for a short a,b pillar

 

If the courtesy lights work when the dome over ride switch is out, then the circuit works and you have a door pin that is staying closed when it should open after the door is closed. To diagnose this, you basically have to remove & disconnect each door pin & test it for proper operation (closed when extended, open when pressed). I believe that the front doors will have the switches integrated into the latch assembly, but this could depend on whether you have the CTD (content theft deterrent) option. If 4dr, the rear doors should have pins in the jam. The tailgate will have a switch near the glass latch and if you have the lift-gate option (all up), it will have one down at the lift gate latch in the lift-gate itself.

If it all checks out, then you have a short to ground in the ground loop for the door switches somewhere. This can be a royal pain to locate, but start at each of the door conduits.

Basically, the door switches activate the courtesy lights by grounding the circuit. If the ground loop wiring shorts to ground anywhere along the harness, it acts just like when a door is opened.

 

That button turns your light off in regards to your door pin switches, check the two front one driver's and passengers I suspect the pin is broken off one of them making the system think a door is open all the time.