No headlights/ rear defrost grid stuck on/ RS rear lower brake light stuck on

[07turd]

Hey Al,
New to the site
I’m looking for some insight on my 07 Tahoe LT weird stuff going on

I am having all sorts of lighting and random issues. First my low beam head lights do no come on. I then swapped the relay with another relay for the headlights no change. I then inspected both 20amp fuses good. I’ve replaced the fuse block under hood and headlight switch. No change. High beams do work when commanded on. I removed the fuse block and tested both LF and RF low beam circuits at under hood box with a power probe commanding them on with power. They did in fact came on and both worked. I then went to the BCM found the ground control at BCM with under hood fuse block on headlight switch on and snipped the wire and manually grounded it. Again headlights did not come on. I’m kinda at a loss.

Now with the truck off key out of the ignition the RR Lower stop light bulb and running bulb are stuck on. So again went to bcm and simply unplugged the brown connector that grounds it lights DID NOT go out. I then removed the brand new 500 fuse block and the light went out. So again scratching my head.

I also have have a wierd issue where the airbag light will come on and go off. I tried scanning it for code with a tech 2 and no communication with the module.

Lastly the left side turn signal in the rear will not flash. I checked the bulb bulb was indeed good. I checked the tail light harness with a the power probe light indeed it is good.

Any insight would be greatly appreciated. I do have access to GM global connect for wire. Diagrams and diagnosis with again no luck.

Thank you all

 

[Doubeleive]

kind of need some background information
like....
did this happen out of the blue or did you buy it like this
what modifications are done? such as led lights or anything aftermarket
any rust?

 

[07turd]

I did not buy it this year have had it for 4 years. Yes it randomly started happening. The truck has minor rust PA car. I live in upstate NY yes it has all LED light. I know it is not the LED lighting. I swapped them out with halogen bulbs it did not change anything

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving clarifying questions from the knowledgeable folks on this Forum, and others will chime in.

 

[mikez71]

I've heard some of the relays can be plugged in backwards, not sure if that applies here.

Was the wire you cut a white wire? (headlamp switch to bcm






-

 

[Doubeleive]

the light wiring on these truck is really wierd. I would try disconnecting the rear lights at the pigtail under the bumper and see if the headlights work then.
I suspect you have a bad ground or crossed wires somewhere. It's just going to take some troubleshooting to figure out.
process of elimination go down to 1 light if you have to, test it and then add one at a time.
srs light is going to be a seperate issue, first thing to check is the front impact sensors they get corroded and bulge/expand up like a defective phone battery.

 

[07turd]

Hi all I did locate the short on the vehicle wires leading into the fire wall coming from the fuse block are shorted against the inner fender where the plastic and metal meet. I had to cut a small section out of 6-7 wires and re solder them with some fresh tape and protective layer it is good to roll.

 

[PopoPackage2011]

Hi all I did locate the short on the vehicle wires leading into the fire wall coming from the fuse block are shorted against the inner fender where the plastic and metal meet. I had to cut a small section out of 6-7 wires and re solder them with some fresh tape and protective layer it is good to roll.

Is it a PPV cop car by any chance or Fire dept truck?

 

[petethepug]

Thank you for letting us know it has had all the lights replaced with LED. The BCM does not like LED’s other than what it engineered for.

Try undoing the LED and see if all goes back to normal. Essentially every manufacturer has free reign to design the diodes circuitry however they like. CREE is the standard of excellence for led but anyone can claim their bulbs are made by them.