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Troubleshooting Brake Controller and Trailer Not Having Brakes  


2020 f150 dash says trailer connected, when I squeeze the controller is says trailer disconnected and I have no brakes. Cleaned all connections on the tongue to no avail. Re packed and adjusted brakes. Help please


Helpful Expert Reply:

It sounds like you are having brake controller issues with your truck, and I can give you a number of troubleshooting steps to try and help you figure out the issue. I'm not 100 percent sure what you are referring to by "squeezing" the brake controller, so I can't offer advice there but there are numerous other things you can check.

What you will need to do is find out if the issue is on the brake controller, truck, or trailer. To test the brake controller, sever the blue wire a couple inches from the back of your controller. Then use circuit tester # PTW2979 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.

If the controller tests fine, reconnect the blue wire and move on to the truck side trailer connector. Often, corrosion or dirt may be the cause of a short in a trailer connector. Check the plug to see if there is any type of corrosion built up that may be hampering its functionality. You mentioned cleaning the connections on the tongue, but I'm not quite sure if that meant the trailer connectors.

You will also want to test the brake output pin on the 7-way socket; it should only show power with the brake controller when you press 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. The short would be due to something like frayed or damaged wires.

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, though it sounds like this was a step you may have done already since you mentioned cleaning connections on the tongue.

Finally, 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 use a multimeter and follow the help article I have linked to guide you.

I have also attached some help articles on testing and troubleshooting brake controllers for you to check out which I strongly recommend reading.

expert reply by:
Kyle S

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