Cargo Light Switch Sanity Check - Is that really all the cargo switch does?

[J_T_Beal]

Looking for anyone who might be able to provide a sanity check on something. I have a 1997 3500 Crewcab. It has the standard cargo light switch in it. I was going to splice into the lines and put in some LED strips under the bed rail for improved bed lighting. After a few test and checking the service manuals, it looks like the cargo light operates the same as the courtesy lights with one exception. When the cargo switch is off and the interior courtesy lights are on, the cargo light will not illuminate.

Construct 1: Courtesy lights are not overridden. Cargo switch is on. A door is opened. The courtesy lights and the cargo light come on.
Consctuct 2: Courtesy lights are overridden. Cargo switch is on. A door is opened. The courtesy lights and the cargo light DO NOT come on.
Construct 3" Courtesy lights are not overridden. Cargo switch is off. A door is opened. The courtesy lights come on and the cargo light stays off.
Constructe 4" Courtesy lights are not overridden. Cargo switch is on. Dimmer rheostat is turned up to max and the courtesy light and the cargo light come on.

So the switch only stops the cargo light from coming on with the courtesy light. Its not like it really turns on the cargo light by itself.

The schematic indicates the switch gets its power from the courtesy panel.

Is that really true?

 

[AK49BWL]

You are 100% correct. It's also easily changed by simply grounding the white wire from the cargo/brake light assembly, then the cargo light can be turned on and off independently.

 

[J_T_Beal]

Freaking awesome! Thank you!!!

 

[GoToGuy]

I was told by a GM tech it was to prevent it being left in the " on" position, and a white light shining against traffic behind you. That's what he said.
I have eight led light assemblies that I'm mounting under the bed rails controlled by another cargo switch to illuminate the bed floor area.