Troubleshooting Trailer Brake Controller No Longer Showing Power to Brakes After Short On 7-Way

Published 03/08/2023

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Digital Multimeter with 42" Long Test Leads - LED Display

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Question:

I was in the process of replacing the 7 pin connectors on a 2004 dodge ram 2500 Cummins and accidentally shorted out the trailer brake pin to ground. I have checked all fuses and checked for power at the fuses and everything checks out ok but I still have no power at the trailer brake pin on the back of the truck. My question is, did the controller get fried? The power light still comes on and turns orange when the brakes are pressed. I cant find the wiring schematic online but Im thinking that the fuses control the module then the power goes out from there to the rear of the truck. Is this correct?

asked by: Jesse

Expert Reply:

It is possible that your trailer brake controller was damaged when the output wire was shorted to ground. There is also a chance the wiring from the brake controller to the 7-way was damaged in the factory harness. You can verify if your controller is still putting out power with a Multimeter # PT89ZR. And connecting to the trailer brake output wire on your brake controller. This is generally the blue wire but be sure to verify with your brake controller as it sounds like you are referring to a factory controller.

If your controller is putting out power on the blue wire you will want to start at the back of your 7-way and follow the harness forward to determine if you can find a spot where the power begins to work. This can be done with the multimeter or a Test Light # PTW2993. This test light is often easier to use as you can probe inside the wiring more easily.

If you are using a factory controller the power is sent from one of the control modules as the factory controller is only a switch. Aftermarket controllers act as the control module as they have their own circuitry.

expert reply by: Bud M