How To Connect A Truck Bed Topper Third Brake Light To The Wiring On A 2022 GMC Sierra 2500

Updated 07/13/2022 | Published 07/05/2022

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Question:

I have a 2022 GMC 2500 and I want to hook up a switched light and 3rd brake light on my topper I want to hook it to my fifth wheel plug in the box What do I need so the brake light doesnt flash?

asked by: Jamie

Expert Reply:

It sounds to me like your wanting to be able to plug in your light so that you can remove the bed topper as needed. The trailer connector is not designed to do what you're wanting it to do so the best way to connect your topper light to your vehicle's wiring is to do the following steps:

You'll first want to pop out your tail light to gain access to the wiring and find which wire has power when the brake pedal is depressed. You can use a tester # PTW2993 to check the wires for current.

From there we'll use the Hopkins 2-Pole Flat Wiring Extension # HM47965 (you'll cut this 2-pole wiring extension in half) and connect one end to the brake light wire on the tail light and the other end to light on the topper.

You'll need some additional 14-16awg wire to get the connector to exactly where you want them to make it easy to connect/disconnect them. Basically, both lights will have wire spliced onto them with connectors being connected to the additional wire and meeting somewhere in between.

You'll want to connect the red wire of the # HM47965 to the power wires for the lights and the white wires can just be grounded to the frame of your vehicle.

A switch can be run anywhere between these two lights but would be kind of pointless to add in since the light is only a brake light and not a light used for visibility of your truck bed. Since this only receives power when your brake lights do it won't flash and thus won't require any extra converters.

expert reply by: Kevin C