So I'm new here and have a 1997 sierra sle 1500 with a quick question about the wiring for the 3rd brake light. My third brake light doesn't always work and I figured I would surprise my inspection guy this year with it working. Since I had today off I did some testing and got the brake lights to work and the cargo lights to work with the switch. I am missing power on 1 white wire. I thought it was a courtsey light but not 100% sure (the lights on the door and dome light come on when I open the door).
4 wire connector
- Top left white wire - 12 volts when pushing on brake pedal.
- Top blue/white wire - 12 volts when cargo lamp switch is on
- bottom left white - no voltage
- bottom right black - ground
4 wire connector
- Top left white wire - 12 volts when pushing on brake pedal.
- Top blue/white wire - 12 volts when cargo lamp switch is on
- bottom left white - no voltage
- bottom right black - ground