Troubleshooting Turn/Brake and Electric Trailer Brake Issue on 2002 Ford F-150  

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Expert Reply:

When all functions work except for one with your trailer lights, you start at that location. So at the rear tail light, you will first want to check the light bulb for that function. Next you will use a circuit tester like # PTW2993 to see if there is signal at that location. If there is, then you know there is power getting to that location and need to check the ground which is normally in the mounting hardware. It needs to be connected bare metal to metal.

If that doesn't solve the issue, then I recommend disconnecting the trailer and cleaning the connection on both sides using some sandpaper or steel wool. The likely issue with your trailer brakes is that they are getting a signal from another pin. With your circuit tester, test the pin at the 5 o'clock location while hitting the manual override on your brake controller. If you get an increasing brightness to the tester as you slide the manual override on your P2 # 90885 then the controller is working properly. If not, you will want to cut the blue wire behind your controller about 6 inches back and test the wire in that location in the same way. If it works properly there, then you will run # 10-1-1 wire from that location back to your 7-way. If it doesn't work there, you will need to replace your controller.

Getting back to the connector at the bumper, you will want to add dielectric grease # 11755 to keep the connector from corrosion. This will keep moisture and debris out of your connections.

If everything works at the trailer connector, I recommend running a new wire on the trailer side to that stop/turn on the right side using # 16-1-1. If the truck side isn't working, then you will want to check fuse #23 and fuse #19 and #108 for brake controller. These locations can be found in your owners manual.

expert reply by: Jason S

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