No Trailer Brake Signal on Factory 7-Way Using Prodigy P2 Brake Controller on 2003 F-250  

Question:

Expert Reply:

Given the 11-year-old age of your vehicle (and presumably its 7-way factory-installed trailer connector) the issue you are having with no brake signal at the brake circuit pin on the 7-way could be a result of a corroded or damaged 7-way. You can use # HM40975 as a replacement for a factory 7-way.

First I suggest you carefully inspect both sides of the F-250's 7-way looking for any signs of damaged wire, worn insulation or even slight greenish or whitish discoloration. Corrosion does not have to be severe, like rust, to affect signal transmission. If there is any green or white film on either the pins or the leads at the back of the 7-way then you might replace the connector. Check the wire leading to the brake circuit; trace it back from the 7-way socket looking for cracks in the insulation, paying particular attention to spots where the wire has to bend or where it might contact the truck frame. Any suspect wire could be causing a short and should be replaced.

Although the Tekonsha Emulator # 6562 is helpful is testing the 7-way socket to test further in the system you will need a probe-style tester like # PTW2993, which is demonstrated in the linked video.
Apply your tester to the blue wire leaving the P2 # 90885; press the manual override (not the brake pedal, as it will not generate a signal when you are still). If you get a signal on the blue wire then you know the controller is sending its output correctly and that the issue is downstream in the wiring. Next test the blue wire leading to the 7-way just before it enters the socket. If signal is there with the manual override pressed then you know the issue is the 7-way socket itself.

If the above steps do not reveal the issue you can check your fuse box looking for any fuse receptacles labeled trailer or tow and replace the fuses as needed.

expert reply by: Adam R

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