Wiring Third Brake and Dome Lights in Truck Bed Cap on a 2008 Silverado Crew Cab  

Question:

Expert Reply:

You will need to tap into the Silverado 7-Way trailer connector wiring (or find the wires tucked in around the spare tire if there is no trailer connector) to provide both brake light and dome light power. Please refer to the attached photo. These wires may be taped up together to protect them. I suggest you use a circuit tester like # PTW2979 to ensure proper identification of the wire functions. Often they are color coded but since there is no guarantee that the wire colors will correctly correspond to the functions, testing is recommended.

Usually the light blue wire in the Silverado harness carries the signal for a topper brake light. With a helper pressing the brake pedal, confirm the vehicle brake lights come on and apply the circuit tester to the light blue wire to check for a brake signal on this wire. If you detect a signal only when the brake pedal is pressed, you have the correct wire for the topper third brake light.

Next you will need to test to identify the wire carrying continuous 12-volt power from the battery; this wire will power the dome light. You will also need an automotive toggle switch to turn the light on and off. I suggest you check on the ARE website to identify your topper and confirm the amperage draw for its dome light, or you can inspect the light housing for this information. You can then select an appropriate on/off light switch at an auto parts store that can safely handle the current load for the dome light.

expert reply by: Adam R

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