Troubleshooting Lack Of Power To The Running Light 7-Way Pin On A 2012 Ford F-250

Question:

2012 f250 power stroke, no trailer running lights at 7 pin connector at back of vehicle. all other lights work. customer states he hooked truck up to bad trailer and lost all lights. i found blown fuse for 12 volt power. replaced and got all lights working except running lights. fuse 26 is good. tested with ohm meter. fuse 30 on the interior fuse box tests good. have power coming in and out on both fuses. i removed drivers side battery and battery tray/ coolant reservoir, disconnected connector under coolant reservoir and can connected test light to battery power and send power down the trailer running light wire and can get 7 pin tester to light up. tested resistance from 7 pin connector all the way to fuse box and i have about 0.5 ohms of resistance using 30ft test leads. running lights on vehicle work. removed running light relay under hood and supplied power and ground to relay and can here it clicking. im thinking body control module fried when bad trailer was connected but i have no wiring diagrams to test for power coming out of module, Thoughts?

asked by: Cody

Expert Reply:

Hey Cody,

The fuse diagram I'm seeing online lists the trailer running lights have a fuse in position 26 and relay in position 29. This diagram could be wrong but definitely worth checking with the diagram on the fuse block cover to see if it's the same function. As for testing the control module, you need to reach out to Ford directly for a wiring diagram, otherwise you'll just have to trace the wiring from the fuse block to wherever the module is located and then test the wires coming in and out to see if the module is the issue.

expert reply by: Kevin C