No power at Brake Controller Harness
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5th Gear
Joined: Feb 2026
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No power at Brake Controller Harness
Hi everyone, new guy here. I need some assistance with adding a brake controller to my 2008 F-150 xl regular cab 2wd.
I bought premade wiring harness to connect a controller, but after getting it all plugged in I am getting no power to the controller.
I’ve checked the kick panel fuse in position 105 and swapped in a relay to R05. Still nothing. Is there anywhere else I need to check or add a fuse or relay?
Thanks in advance.
I bought premade wiring harness to connect a controller, but after getting it all plugged in I am getting no power to the controller.
I’ve checked the kick panel fuse in position 105 and swapped in a relay to R05. Still nothing. Is there anywhere else I need to check or add a fuse or relay?
Thanks in advance.
Fleet Mechanic
Joined: Jan 2023
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*****Edit*****this information is wrong . I was looking at a 2001 truck****
Fuse 108 is trailer tow electric brake 30 amp maxi fuse. This is the fuse box in the engine compartment.
Fuse 108 is trailer tow electric brake 30 amp maxi fuse. This is the fuse box in the engine compartment.
Last edited by Don Ridley; Feb 20, 2026 at 08:34 AM.
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5th Gear
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Thanks. Ok so dumb question…where is the underhood fusebox? The only thing I’ve been able to find is a small rectangular box mounted on the driver side fender with a couple of fuses in it.
Fleet Mechanic
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5th Gear
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5th Gear
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Last night I started the process of eliminating the less likely causes. I unplugged the prefab harness and started comparing the wire locations in it versus the truck plug.
Well, the red and black wires were put into the prefab connector on the wrong side of the plug bank!
I disassembled the plug, moved the wires over to the correct side, and now the controller has power and is working.
Thank you to everyone that assisted helping to narrow down this problem!
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