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No Power on Red Brake Controller Wire when Brake Pedal Pressed on a 2013 Toyota Tundra


I installed a Tekonsha P3 brake controller in my 2013 Toyota Tundra with the wire harness specifically designed to connect the controller to the trucks factory wiring. The brake controller only works when using the lever, it has never worked when the brake pedal was depressed. Last week, I used a test light to confirm the fuse 15amp fuse # 10 under the hood was good, in addition all three brake lights work, but there was no power coming through the red wire when the brake pedal was depressed. I replaced the brake light switch a couple days ago because I was told that was the most likely culprit. Ive since confirmed all three brake lights still work, but the trailer brakes two different trailers only work when using the lever. The black wire is hot, the blue wire is hot when the lever is used, white wire is grounded to the firewall, and red wire does nothing. What should be my next steps in troubleshooting? Is it possible the wire harness/adapter is not wired correctly? Thank you!


Expert Reply:

The wiring harness you should be using on your 2013 Toyota Tundra is # 3040-P. While it is unlikely it is wired incorrectly it is possible. You can use your test light to test the connector on the vehicle (where 3040-P plugs into) and see if it has power when you step on the brake pedal. If it does then check to see if the red wire is connected in the corresponding location in the harness. If not you can move it.

If there is no power then there is something amiss on the vehicle side that will need to be tracked down. You mentioned check a fuse but didn't say what that fuse was. Check the stop light or CHMSL fuses if you haven't already. Its likely not this since all of your brake lights work but you never know!

Another option is to attach the brake controller red wire to the brake switch instead. The correct brake switch wire should be the orange wire on your truck but you can use the test light to verify that.

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