How to Wire a Brake Controller in a 2018 Thor Gemini Motorhome
Updated 09/12/2025 | Published 05/27/2025
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Question:
Hello, My brother has a 2018 Thor Gemini motorhome, on a Ford Transit T350 chassis, and it has the tow package. Can I use the blue wire coming from the factory 7 pin trailer connector, if I find it in the factory wiring connector under the cup holders, run it to one of your aftermarket brake controllers, and get the brake signal from the violet/white wire on the brake light switch, and make the aftermarket controller work? Thanks
asked by: Brian
Expert Reply:
Hey Brian. You can so long as that violet/white wire on the brake light switch only has power to it when you press the brake pedal. You want the cold side of the brake light switch. You can use a circuit tester like item # PTW2993 to identify it.
If you can't find the blue wire or follow it from the 7-way connector, you can use the 10 Gauge Wire - Blue Primary - Per Foot item # 10-1-1 to run your own. It's sold by the foot.
What is your brother looking to tow with his motorhome?
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Jerred H.
9/12/2025
Hey Brian, did you have a chance to test the violet/white wire with a circuit tester to ensure it only has power when the brake pedal is pressed? I’d love to hear how it worked out for your brother's motorhome setup, as it could give others confidence when setting up their brake controllers.