headlights don't work off switch

[02YukonD]

I'm in a sticky situation.. I have a 02 Tahoe z71 and my headlights come on and stays on as long as the truck is running. i replaced the master switch with one out the junkyard. The master headlight switch doesn't work when the truck is running. I tried pressing the dome override button 4x's but that didnt work. I was gonna change the ambient light sensor next week.. is there anything else that it could be? Can someone point me in the rite direction.

 

[ScottyBoy]

You said it doesn't work "when the truck is running". Does that mean that it functions perfectly fine when the engine is off?
If it does work fine with the engine off, try it with the parking brake engaged. If they go off when the parking brake is engaged, then I would say you definitely need to replace the ambient light sensor. I had this same problem and I really placed mine a few years ago. It was under $20 at my local Chevy dealer.

 

[02YukonD]

Oh OK.. yes the headlight switch turns the headlights off and on when the engine is off.. imma try parking brake in a few minutes

 

[02YukonD]

Yea the headlight went off when the parking brake on..

 

[omega123]

Wow mine just started doing this a few days ago and im writing this down to try on my next day off.

 

[02YukonD]

Do anyone know what else it could be?? I changed the ambient light sensor and that did nothing.

 

[02YukonD]

Could it be the bcm?? or should I try ordering a brand new switch. My truck is having a few issues like the interior light don't come on when the driver door is open, the instrument cluster light went out, and the headlights problem

 

[ScottyBoy]

Do you install a new ambient light sensor? Or a used one from a junkyard?

 

[02YukonD]

I installed a new one. The genuine gm part

 

[ScottyBoy]

Do you recall the part number? The part for 00-02 trucks is different than the one for 03-06 trucks. If you DID install the correct one, I'm not exactly sure what else it could be?? I had the same EXACT symptoms as you, and the parts guy a few he dealership told me to check it by putting on the parking brake (like I told you to do) and if the lights went out then it's the sensor. I replaced the sensor and all has been fine ever since.
Only other thing that I can think of would be the headlight switch. You mentioned that you press the dome override button and it doesn't affect the headlights. I remember when my headlights were doing this, I pressed the override button and the lights DID shut off. But every other symptom was exactly the same. Maybe that headlight switch is bad?