Interior light help

[cmoore123]

I have a 99 yukon Denali my interior lights will not work when any door is opened.

Ive replaced the headlight switch thinking the dome overide switch was dead because you can manually turn the lights on any suggestions?

 

thanks

[skills4lou]

I have a 99 yukon Denali my interior lights will not work when any door is opened.

Ive replaced the headlight switch thinking the dome overide switch was dead because you can manually turn the lights on any suggestions?

 

thanks

 

<{POST_SNAPBACK}>

 

 

Just guessing here: does your truck have a "dome light override switch"? My 94 Sub and 98 p-up both have one. Does exactly what you described, and it my just need to be turned off.

[GM-Tech]

Just guessing here: does your truck have a "dome light override switch"?

 

Note that he said he replaced the headlight switch because he thought the "dome light override switch" was dead. So yeah, he has one and knows it.

 

I'll have to look at schematics and see what may be going on when I get to work.

[GM-Tech]

As I suspected, it's a somewhat complex system that can't be diagnosed from "the lights don't go on when the door is opened."

 

Control is largely through the body control module. The drivers door input is separate from the remaining doors. The odds that every switch in every door has gone bad at once is zero I'd say.

 

Pull the headlight switch out and with it still connected and a door open, see if terminal B, a white wire, has a ground. The body control module provides a ground to the dome lights through the override switch which comes out on terminal B.

 

Basically, the switch in the headlamp switch that you can use to manually turn on the dome lights, and the wire from the override switch (term B) end up at the same spot, a splice that provides ground to all the lights. If you can manually turn on the dome lights, then all that remains is the white wire from Terminal B to that splice, the override switch (which you've already replaced), the wire from the BCM to the override switch or the BCM itself. OR, the BCM is inhibiting dome lights for some reason.

 

Would be nice if you could hook up a scanner and see if the BCM is requesting the dome lights to be on or not. That'd elminate a lot.

[cmoore123]

As I suspected, it's a somewhat complex system that can't be diagnosed from "the lights don't go on when the door is opened."

 

Control is largely through the body control module.  The drivers door input is separate from the remaining doors.  The odds that every switch in every door has gone bad at once is zero I'd say.

 

Pull the headlight switch out and with it still connected and a door open, see if terminal B, a white wire, has a ground.  The body control module provides a ground to the dome lights through the override switch which comes out on terminal B.

 

Basically, the switch in the headlamp switch that you can use to manually turn on the dome lights, and the wire from the override switch (term B) end up at the same spot, a splice that provides ground to all the lights.  If you can manually turn on the dome lights, then all that remains is the white wire from Terminal B to that splice, the override switch (which you've already replaced), the wire from the BCM to the override switch or the BCM itself.  OR, the BCM is inhibiting dome lights for some reason.

 

Would be nice if you could hook up a scanner and see if the BCM is requesting the dome lights to be on or not.  That'd elminate a lot.

 

<{POST_SNAPBACK}>

 

 

[cmoore123]

well checked for ground at term b no ground so i guess that means poss bad body computer i guess i need to have it scaned thanks for the help.

[skills4lou]

Just guessing here: does your truck have a "dome light override switch"?

 

Note that he said he replaced the headlight switch because he thought the "dome light override switch" was dead. So yeah, he has one and knows it.

 

I'll have to look at schematics and see what may be going on when I get to work.

 

<{POST_SNAPBACK}>

 

 

 

OOPS. I guess I should not be allowed on the net after 10pm.