Troubleshooting Trailer Brakes Not Functioning When Connected To Truck But Work On Trailer  

Question:

Expert Reply:

It sounds like there is an issue with either your Brake Controller like the # 90195 or with the wiring and 7-way connection on your truck since you were able to confirm that the brakes on the trailer are working.

I recommend starting with the brake controller itself, first ensure that it is powering on and recognizing when the trailer is connected. If the brake controller does not power on you will need to check the fuse of relay on your specific truck. If it is not showing that a trailer is connected there is likely damage to the wiring going to your 7-way or an issue with the 7-way connector.

You will need a Multimeter #PT29ZR to test the brake controller output. With the brake controller on and set to maximum output you should see close to battery voltage coming out of the blue wire on the back of the brake controller when the brakes are manually activated. Be sure to manually activate the brakes, as a proportional brake controller it will only activate the brakes when it feels the inertia of stopping on your truck when the brake pedal is pressed. You can test the voltage again at the 7-way and you will likely see some drop in voltage(usually 1 volt) due to the wiring resistance in your truck. If you have no voltage at the connector be sure to test the wire going into the connector to determine if the wiring is faulty of the 7-way itself.

If you find something wrong with either the wiring, 7-way or brake controller let me know what truck you have and I can help you find the correct replacement parts needed for your truck.

expert reply by: Bud M

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