Cargo Light - simple fix or another missing function

[Jason Caswell]

Sorry for the simple question.  I have a 2020 Silverado 2500 HD and I cannot figure out how to get the cab mounted cargo light to come one.  The obvious button that illuminated the permitter lights, in-box lights, and tailgate light doesn't seem to turn on my cab mounted (up with 3rd brake light) cargo light. 

 

Am I missing something or is this another delete from gm (e.g console storage, read map pockets,...)

[kf9yr]

On my truck it comes on with the button for the rear mirror mounted lights.

I have a GMC AT4 with the towing mirrors. I’m not sure if all the mirrors have the lights or if there is a button for the cargo light when there aren’t.



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[Jason Caswell]

Thanks.. yes I have the mirror lights as well.   cargo light button seem to work for me on those as well as the rear box lights and tailgate light.   

 

strange

[redwngr]

Are you in P or R or N?

First 2 modes should give cargo light (CHMSL) on. 

Do any of the modes work?

 

If the vehicle is in P (Park), R (Reverse), or N (Neutral) the Cargo Lamp Switch causes the lights to cycle through the following states for each button press:

- Initial Press:
- CHMSL/Cargo Bed Lights - On

- Cargo Mirror Lights - On
- Cargo Switch Indicator (if equipped) - On

 

- Next Press: (if with in 5 seconds of the previous button press):
- CHMSL/Cargo Bed Lights - On
- Cargo Mirror Lights - Off
- Cargo Switch Indicator (if equipped) - On

 

- Next Press:
- CHMSL/Cargo Bed Lights - Off
- Cargo Mirror Lights - Off
- Cargo Switch Indicator (if equipped) - Off 

 

 

If the High mounted cargo lamp (or the 3rd brake light) is burned out, the manual has instructions for changing (pg 369 for '20 Sierra)

 

 

 

[Jason Caswell]

22 hours ago, redwngr said:

Are you in P or R or N?

First 2 modes should give cargo light (CHMSL) on. 

Do any of the modes work?

Park and CHMSL is Off in all modes.   all other lights work just as you have described (proper sequence etc..)

 

Thanks for the source to troubleshoot the burnt out light.   Unfortunate if it was burnt from new. 

[Ron h]

So I went to install aftermarket cargo lights. The wiring is in the back behind a blank plate. All plugged in and turned the switch on. The mirror lights and third brake light lights come on but no power to the bed cargo wire. Any suggestions?

[carkhz316]

In the right side instrument panel fuse box, check fuse F34DR. Its specifically for the CHMSL cargo light. There is also a CARGO LAMP relay in that same fuse box that could be bad. The other cargo lights (bed and mirrors) are directly controlled by the BCM, hence why they could be working but not one on top of the cab.

Edited January 8, 2024 by carkhz316