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Why Would Camper Shell Third Brake Light be Dim and Blink When Not in Use on Truck


this is what I red from you. below I did the blue wire and is not very bright when I hit the brakes. I locked up my truck 2015 Silverado and noticed the new brake light blinks every 20 or so seconds. I watched it for 5 minutes or so and it never stopped blinking. Nothing was on, truck locked up for the night. what could it be? thanks in advance. Expert Reply: If you follow wiring harness feeding the 7-way trailer connector from the bumper up toward the spare tire and peel back the wire loom, you should be able to find an additional blue wire in the harness. The blue wire carries the 3rd brake lamp signal for your bed topper.


Helpful Expert Reply:

Sounds like you are using your brake controller output circuit for the third brake light of a camper shell. This would explain the dim illumination and it pulsing every few seconds as that is how controllers test for trailer connections. Test other wires near the blue wire you found to see if you can find a dedicated brake circuit that sees full 12 volts when brakes are applied and none when released.

There are a couple of places you can access a dedicated brake light only circuit on your 2015 Chevy Silverado. First, you can tap into the circuit behind the third brake light on the cab of the truck. You can also get the signal from the CHMSL or stop light fuses. Use the vehicle owners manual and/or power distribution box lid to locate the fuses for the center high mount stop light (CHMSL) or stop light circuit.

helpful expert reply by:
Jameson C

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