'07 Yukon No running/parking lights? Need help.

[mudyukon]

Hello,
I have an -07 Yukon XL. My running / parking light quit working. This means at night I have no taillights on. The front amber lights do not light up. Also the license plate light too does not I believe. Brake lights work when pedal is pressed.

I checked fuses and relay. Now when I jumper the relay for the running lights (pin 30 and 87) the running lights work. So I know all my wiring past the relay is good.
What would be next? See if the BCM is outputting power to the lights? I was looking for a BCM pin diagram and haven't found one yet.. I would appreciate any help, thanks!

 

[Trey Hardy]

Hello,
I have an -07 Yukon XL. My running / parking light quit working. This means at night I have no taillights on. The front amber lights do not light up. Also the license plate light too does not I believe. Brake lights work when pedal is pressed.

I checked fuses and relay. Now when I jumper the relay for the running lights (pin 30 and 87) the running lights work. So I know all my wiring past the relay is good.
What would be next? See if the BCM is outputting power to the lights? I was looking for a BCM pin diagram and haven't found one yet.. I would appreciate any help, thanks!

Bulbs not blown?
My rear tag lights always falls out it’s aggravating.
Won’t the taillights come on if you cut the headlights on instead of leaving it in auto?
Sometimes these bulb sockets/plugs get corrosion in them and won’t make good connection my buddy at the shop has had to change quiet a few on a couple 07-13 models

 

[mudyukon]

Bulbs not blown?
My rear tag lights always falls out it’s aggravating.
Won’t the taillights come on if you cut the headlights on instead of leaving it in auto?
Sometimes these bulb sockets/plugs get corrosion in them and won’t make good connection my buddy at the shop has had to change quiet a few on a couple 07-13 models

Bulbs are good, they all light up (front and back) if I jump the relay for them... They do not come on in auto mode on the switch, or when I turn the dial to turn them on manually. Somehow the relay is not get turned on. I guess the BCM is responsible for that?

 

[Geotrash]

Hello,
I have an -07 Yukon XL. My running / parking light quit working. This means at night I have no taillights on. The front amber lights do not light up. Also the license plate light too does not I believe. Brake lights work when pedal is pressed.

I checked fuses and relay. Now when I jumper the relay for the running lights (pin 30 and 87) the running lights work. So I know all my wiring past the relay is good.
What would be next? See if the BCM is outputting power to the lights? I was looking for a BCM pin diagram and haven't found one yet.. I would appreciate any help, thanks!

Can we assume you replaced the relay as well?

An alldatadiy subscription is gold for situations like this. They have all of the wiring diagrams and troubleshooting steps laid out.

 

[mudyukon]

Can we assume you replaced the relay as well?

An alldatadiy subscription is gold for situations like this. They have all of the wiring diagrams and troubleshooting steps laid out.

Yes swapped the relay with the starter relay next to it..

 

[B-train]

Maybe a faulty switch?

 

[mudyukon]

Maybe a faulty switch?

Its a possibility, but when the switch is in auto it makes the headlights and instrument lights come on.

 

[mudyukon]

I've been searching the web for a BCM pin diagram with no luck yet. Sounds like the BCM supply a ground to the parking lamp relay. I just have to figure out which wire on the BCM.

 

[Geotrash]

I've been searching the web for a BCM pin diagram with no luck yet. Sounds like the BCM supply a ground to the parking lamp relay. I just have to figure out which wire on the BCM.

Yes, the BCM supplies the ground. Don’t have a color code chart for you but this may help. Note that it’s for a 2012 Denali though.

 

[mudyukon]

That does help, Thank you. It looks like a light blue wire going into the BCM, and Dark Blue coming out. Ill have to see if I can locate those.

 

[Juanadon21]

That does help, Thank you. It looks like a light blue wire going into the BCM, and Dark Blue coming out. Ill have to see if I can locate those.

I'm have the exact same problem. I've checked everything you have. Did you find a solution by chance

 

[mudyukon]

Ill let you know what I find. I am going to put a scan tool on it in the next few days. I am thinking the BCM is the problem, but I'm not totally sure yet.

 

[Juanadon21]

Ill let you know what I find. I am going to put a scan tool on it in the next few days. I am thinking the BCM is the problem, but I'm not totally sure yet.

I put the relay in part way. An put a wire from the body for ground to 86 and the relay would engage. All lights would work. So I'm going to test from 86 to x5 pin 24 to make sure the wire is good. If it is I know the bcm is bad. Also I had power from the switch to the bcm. Light blue. So worst comes to worst ill pull pin 24 and wire a toggle switch from it to ground near the column. So I can flip it on an off till my new one comes in.

 

[mudyukon]

I did some more testing. My BCM appears to be good. When I turn on the parking lights, I am getting a ground signal on dark blue wire pin 24 on the BCM. However this signal is not making it to pin 86 on the parking light relay in the fusebox. When I ground that relay pin 86 my parking lights turn on as well. I tested for continuity on the d-blue wire on BCM to pin 86 on the relay. I got no continuity leading me to believe the wire is bad.

I may run a new wire to the relay. I know the wire on the BCM, but I can't yet locate the wire going to the relay under the hood.

 

[Fless]

Have you pulled the top section of the fusebox off, and inspected the connections underneath for clean contact?

 

[mudyukon]

Have you pulled the top section of the fusebox off, and inspected the connections underneath for clean contact?

I did. I was suspicious of bad contacts under the fuse box because I’m in salt country.. but everything was nice and clean. When I had it off, I was able to find the dark blue wire under the fuse box that switches ground to the parking lamp relay. I think I’m going to run a new wire through the firewall from the BCM to fuse box. Its strange that wire would be damaged because it seem well protected with split loom over it. Its difficult to trace the entire length, because that wire just goes into a large bundle of wires.

Update - ran the new wire and that fixed it. Thanks for everyone’s help!

 

[Geotrash]

I did. I was suspicious of bad contacts under the fuse box because I’m in salt country.. but everything was nice and clean. When I had it off, I was able to find the dark blue wire under the fuse box that switches ground to the parking lamp relay. I think I’m going to run a new wire through the firewall from the BCM to fuse box. Its strange that wire would be damaged because it seem well protected with split loom over it. Its difficult to trace the entire length, because that wire just goes into a large bundle of wires.

Update - ran the new wire and that fixed it. Thanks for everyone’s help!

Woohoo!!! Nice job on the sleuthing and thanks for following up!