How to Get a Brake Light Signal for ARE Topper 3rd Brake Light on a 2019 GMC Sierra 1500  

SUMMARY - How do I get a brake signal for the 2021 ARE V-Series Topper on a 2019 GMC Sierra 1500. Nobody has specifics on the wiring. - I need to wire an 2021 ARE V-series Topper on a 2019 GMC Sierra 1500. The Sierra has the Prograde trailering System and LED taillights. I bought a Curt 7-pin to a flat 4 connector that was supposed to be wired, in conjunction with a CHMSL Logic Box, and make the third brake light on the topper work. Ive also seen advise that I needed to wire into a connector box above the left kick panel under the dash, although a bulletin from ARE recommends one connector and a wire color, while a TAG bulletin suggests the adjacent wiring block with a different wire color. Other advice from GM Upfitter says there is a dedicated third brake light wire mounted at the rear body Junction Block X63A and it should be used. GM cannot provide a wiring diagram for the truck and no other source Ive contacted has been helpful in providing a definitive solution. From all the forums, Facebook groups, etc. that Ive asked about this, there are a lot of people with general information, but none specific to the 2019 GMC. Some have even said the late year model 2019 GMC Sierra is a unicorn and doesnt fit in any box that makes this easy. I find it hard to believe that there is no easy solution found to this problem between 2019 and mid-year 2024 for this truck and a topper third brake light, which brings us to today. I saw a glimmer of hope in reading through your website in regards to part R044FR. Bud M responded to someone on your QandA regarding a 2023 GMC Sierra with the following title: Parts Needed To Wire Tail Lights Separate From Brake Lights When Flat Towing a 2023 GMC Sierra 1500 I think this answer is in regard to flat towing the truck behind an RV, but it mentions needing load resistors and a 2 to 3 wire tail light converter. With my truck having the LEDs, I would think Id need resistors too. I had a travel trailer camera system that wouldnt work with this truck until I got a 7-pin dog bone connector that smoothed out the voltage issue. It works great now. I need to know exactly what I need to wire the topper so that the topper third brake light works as it should with the truck brake lights without flashing the topper third brake light. I also need to know what wires on the truck I need to tie into, as there are five wires in the loom going into each taillight on the truck. In the connector, there is a red wire alongside a brown wire in one row of the connector and the next row has a light green, a darker green, and a black wire. Ive added a photo of the truck tail light wiring connector. The topper third brake light has only two wires, a blue one and a black one. Thanks for your help and guidance!

asked by: Greg W

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