Added Cab/Clearance lights to a 2025 and they won't light up

[skorpyd]

I mistakenly forgot to order the cab marker lights on my 2025 3500 trail boss.  After looking at the well written post on doing it yourself by hotairgypsy I decided that it would be better left to the professionals.  The body shop at my local dealership got the lights installed and plugged them into the existing plug in the headliner but no lights.

Obviously they have never done this on one of the newer trucks.   This was late on Friday afternoon and I needed the truck for the weekend.  The body shop manager said something about looking for a code number to be able to contact GM with to get another code to allow them to reprogram something. But the number he thought he was looking for wasn't there.

 

I'm just curious if any more knowledgeable or tech savvy people out there have any ideas on what the issue is and how to actually get the lights to work.

[Silverado4x4]

4 minutes ago, skorpyd said:

I mistakenly forgot to order the cab marker lights on my 2025 3500 trail boss.  After looking at the well written post on doing it yourself by hotairgypsy I decided that it would be better left to the professionals.  The body shop at my local dealership got the lights installed and plugged them into the existing plug in the headliner but no lights.

Obviously they have never done this on one of the newer trucks.   This was late on Friday afternoon and I needed the truck for the weekend.  The body shop manager said something about looking for a code number to be able to contact GM with to get another code to allow them to reprogram something. But the number he thought he was looking for wasn't there.

 

I'm just curious if any more knowledgeable or tech savvy people out there have any ideas on what the issue is and how to actually get the lights to work.

That wire harness above the headliner is not for cab lights it's for if you want to install emergency lights for a becon light for plowing etc. I bet if you turn the axillary light switch on the dash they come on if hooked up right.

[skorpyd]

6 minutes ago, Silverado4x4 said:

That wire harness above the headliner is not for cab lights it's for if you want to install emergency lights for a becon light for plowing etc. I bet if you turn the axillary light switch on the dash they come on if hooked up right.

Hmmm, I'll ask them about that Monday.  It sounds like it must have been the right plug end to fit the light harness.

[Silverado4x4]

1 hour ago, skorpyd said:

Hmmm, I'll ask them about that Monday.  It sounds like it must have been the right plug end to fit the light harness.

I would test it by starting the truck and press the auxiliary light switch button on the left side dash, check your owners manual under "Auxiliary Roof-Mounted Lamp" for the location of the button cause it varies on the model and see if they come on. 

[64BAwagon]

My guess would be that the lights are connected to the proper harness but the BCM is not programmed for cab lights and may not be energizing that circuit when the other lights are on. 

[gemarsh]

1 hour ago, 64BAwagon said:

My guess would be that the lights are connected to the proper harness but the BCM is not programmed for cab lights and may not be energizing that circuit when the other lights are on. 

I would say this ^^^.

 

The aux roof light harness is in the back spoiler, by the 3rd brake light. 

[skorpyd]

Lights are working now, Dealer said the fuse must have blown when they connected the harness.

[mmills023]

skorpyd - What dealer did you use to do the install?  It looks like your in Michigan, thats where we are as well.  Also - would you share how much they charged you?

 

Mike

 

[OS RR]

... do our trucks (mines a 24 custom) come with the harness already up there?

 

I was under the assumption they did not after looking at how boostauto does theirs.

[skorpyd]

On 2/1/2025 at 6:45 AM, mmills023 said:

skorpyd - What dealer did you use to do the install?  It looks like your in Michigan, thats where we are as well.  Also - would you share how much they charged you?

 

Mike

 

I used the body shop at Moore Shoreline Motors in Sebewaing

[Jim Blecha]

On 12/15/2024 at 7:10 AM, skorpyd said:

I mistakenly forgot to order the cab marker lights on my 2025 3500 trail boss.  After looking at the well written post on doing it yourself by hotairgypsy I decided that it would be better left to the professionals.  The body shop at my local dealership got the lights installed and plugged them into the existing plug in the headliner but no lights.

Obviously they have never done this on one of the newer trucks.   This was late on Friday afternoon and I needed the truck for the weekend.  The body shop manager said something about looking for a code number to be able to contact GM with to get another code to allow them to reprogram something. But the number he thought he was looking for wasn't there.

 

I'm just curious if any more knowledgeable or tech savvy people out there have any ideas on what the issue is and how to actually get the lights to work.

What kid did you order for your truck?  I have the same truck. 

[jjsima01]

On 12/16/2024 at 6:38 PM, skorpyd said:

Lights are working now, Dealer said the fuse must have blown when they connected the harness.

By any chance do you know what fuse it was?