Wiring OEM Light Bar & OEM Switch 2003 Silverado 1500

[Dustin Luchini]

I have a 2003 Chevy Silverado 1500 with a 5.3 litre v8 motor. I'm currently trying to install a small light bar that has two wires (red and black) to a OEM light bar switch that I bought online. The switch itself has 5 wires coming off the back of it. The colors of the wires on the back of the switch are white, black, orange, gray, and purple. I tried to do a bench test on the light running it through the switch, but the switch would not work. My truck did not come with this option, but I am trying to add it. I did some research online and found that it is the "snow plow prep package" and this switch is normally for the "emergency beacon" on the roof of the cab. I'm having trouble finding a wiring diagram and information on how to install it. Please help. Thanks.

[Jsdirt]

Most switches on modern (when I say modern, I mean in the past 24 years) vehicles are just "signal senders" to a magic box (computer, or module). Not one switch in my '07 Silverado actually sends current to any of the loads - it just tells the BCM (Body Control Module) that I want to activate said component, and the COMPUTER does the heavy lifting.

 

Judging from the size of those wires, it's a safe bet that this switch is no different. Getting it to work the way the factory did will be a colossal pain in the ass. I would imagine a BCM reflash adding the snow plow package options to the truck is in order, so you'll have to factor that expense into the project. No guarantees that will even work once you do it, however. Ahh, the joys of computers ...

 

If it were me, knowing what I know about 12v systems, I'd get my own switch, and just wire it up old school, using a cube relay. Wire the switch to the primary side, and wire the load to the secondary side.

 

That switch could be designed to receive, and step down a 5v reference, so there would be a ground, 5v ref, and signal (to computer). Some of those wires will control LED backlighting inside that switch, so that adds 2 to the mix.

Edited July 9, 2020 by Jsdirt