Troubleshooting Prodigy P3 Showing No Trailer Connected on 2013 GMC Sierra  

Question:

Expert Reply:

Oftentimes when the reading says your trailer is not connected when using the Prodigy P3 # 90195, the cause is connectors that have corrosion or dirt built up and ensuring they are clean inside and out can be a remedy. There are tests you can do as well.

You will also want to test the brake output pin on the 7-way socket; it should only show power with the manual override. If it shows power any other time then there is a short somewhere between the connector and the brake controller you will need to find.

If the truck side checks out then it could be the wiring to the brake magnets or possibly the magnets themselves. Inspect the power wires to the magnets and look for wires that may be pinched or otherwise damaged and fix as necessary. You'll also need to make sure the ground wires are attached to bare metal surfaces, free of any paint, dirt or corrosion.

You'll want to visually inspect the magnets; if you can see the copper windings coming through the magnets will need to be replaced. To test the magnets, you can follow the help article I have linked. Finally, you will want to test the brake controller, so sever the blue wire a couple inches from the back of your controller. Then use a circuit tester such as # PTW2992 to test the end of the blue wire coming out of the controller. It should only have power when you apply the manual override; if it shows power at idle then there is an issue with the controller and it will need to be replaced, although this is unlikely if it is a brand-new controller. Still, you'll want to be thorough and make sure.

I have attached some help articles on testing and troubleshooting brake controllers for you to check out.

expert reply by: Kyle S

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