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Brake Controller Will Work When Using Manual Override Lever But Not When Pressing Pedal  


I have the same issue that I see other people have had. The manual brake override works the trailer brakes but not the brake pedal. Could it be there is a fuse on the vehicle side thats blown? I have a 2007 GMC Sierra


Expert Reply:

Usually, when your brake controller works using the manual override and on when pressing the pedal, the issue is with the red wire connected to the stop light switch.

Using circuit tester, like # PTW2993, check to see if you have any electrical signal on the red wire present when the brake pedal is pressed. If you have no power, check to make sure that the wire has not come loose from the connection on the stop light switch. The red wire is connected to the cold side of the stop light switch wiring. If your brake controller red wire is not connected to the correct wire, or is loose or broken, this would cause the problem you are experiencing.

However, if the red wire circuit checks out, the issue is most likely a faulty brake controller, and you will need to replace the unit.

There should not be a fuse on either blue or red wire circuit of your controller. The amount of amperage that these two circuits draw is very small and insignificant. Also, a fuse installed in line could cause trailer brake failure when in use.

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