2020 Yukon Tail Light Assembly partially working

[GreyWolfJeeper]

Hi All -

I have a 2020 Yukon SLT, and the rear passgenser tail light is not working. In the assembly there appears to be the brake light LED, the running light LED, the turn signal, and the backup light (with a regular bulb). So specifically, the running light LED is not working - everything else seems fine.

I saw all the posts about troubles with the tail light assembly, and instead of trying the repair method, I saw non-OEM assemblies available on Amazon and picked one up for $85.

When I put the new light assembly in, I get the same thing. Running light LED not working, but brake and back up light are fine. So, this seems to indicate it is not the assembly itself (and I should probably get my $85 back).

So, next I checked the fuses. In the main fuse block in the engine department, there is fuse number 43 which disabled the driver's side LED, so I assume fuse number 42 controls the passenger side LED - but fuses looks good. I saw there is a light control module in the wiring diagram, and saw a post saying that one of the BCM fuses may control it, so I checked a bunch of fuses in the internal fuse blocks. Still no bad fuses there.

I next checked the wiring harness connections and they seem okay, with no visible corrosion. I tried following the wiring looking for any obvious breaks, but it is hard to get access to where the wires are tucked away. I didn't see anything bad, with what I could see.

So, I am running out of ideas and wanted to see if anyone had some other ideas before I take it in to a shop?

 

[Tahoe14]

@Doubeleive may be able to help

 

[Doubeleive]

Hi All -

I have a 2020 Yukon SLT, and the rear passgenser tail light is not working. In the assembly there appears to be the brake light LED, the running light LED, the turn signal, and the backup light (with a regular bulb). So specifically, the running light LED is not working - everything else seems fine.

I saw all the posts about troubles with the tail light assembly, and instead of trying the repair method, I saw non-OEM assemblies available on Amazon and picked one up for $85.

When I put the new light assembly in, I get the same thing. Running light LED not working, but brake and back up light are fine. So, this seems to indicate it is not the assembly itself (and I should probably get my $85 back).

So, next I checked the fuses. In the main fuse block in the engine department, there is fuse number 43 which disabled the driver's side LED, so I assume fuse number 42 controls the passenger side LED - but fuses looks good. I saw there is a light control module in the wiring diagram, and saw a post saying that one of the BCM fuses may control it, so I checked a bunch of fuses in the internal fuse blocks. Still no bad fuses there.

I next checked the wiring harness connections and they seem okay, with no visible corrosion. I tried following the wiring looking for any obvious breaks, but it is hard to get access to where the wires are tucked away. I didn't see anything bad, with what I could see.

So, I am running out of ideas and wanted to see if anyone had some other ideas before I take it in to a shop?

I have not had to mess with the k2 tail lights as of yet, but
are you able to take the left/right and switch them (without mounting them) just plug them in? and see if you get the same results?
from pictures it looks like there is the typical short harness from the main body harness up to the housing you may want to check the lower end where it is exposed to the elements.
and each wire you could check with a meter

 

[GreyWolfJeeper]

Thanks, I will try to check each wire with a multi-meter. I didn't think of swapping the left and right light assemblies. I can try that too.

 

[GreyWolfJeeper]

I have not had to mess with the k2 tail lights as of yet, but
are you able to take the left/right and switch them (without mounting them) just plug them in? and see if you get the same results?
from pictures it looks like there is the typical short harness from the main body harness up to the housing you may want to check the lower end where it is exposed to the elements.
and each wire you could check with a meter
View attachment 438123

I checked each wire in the harness, and the green and yellow wires were showing zero voltage. I didn't have the backup light on, so it looks like the green wire is the culprit.

So, now I know the problem is happening somewhere before the wiring harness. Not sure there is much else I can do though?

 

[Doubeleive]

I checked each wire in the harness, and the green and yellow wires were showing zero voltage. I didn't have the backup light on, so it looks like the green wire is the culprit.

So, now I know the problem is happening somewhere before the wiring harness. Not sure there is much else I can do though?

just have to trace it back or patch in the running light from the other side

 

[tom3]

Trailer wiring on this machine?

 

[GreyWolfJeeper]

Trailer wiring on this machine?

Yes, it has the Max Tow package, with the OEM 7-pin connector.

 

[tom3]

One of those pins would have power for the tailights, probably a connector back to the main wire, check for power on the trailer plug. Could be a fault at that connection point.

 

[Fless]

The trailer lights are on a different fuse/circuit. But for grins check that 7-blade connector for cleanliness. Weird things can happen when there's dirt in it.