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License Plate Lamps & Trailer Running Lights Fuses

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Old 01-22-2021, 05:38 PM
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Default License Plate Lamps & Trailer Running Lights Fuses

Hi All,
I have a 2015 extended cab, v8, F150 and am looking for help on a couple of fuses. I'm looking for info as to which fuse controls the rear license plate lamps?
Also, which fuse controls the running lights for a trailer?
Old 01-22-2021, 05:42 PM
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Are you saying that when your Truck is connected with the trailer, you have no lights? Have you checked the output of your trucks plug? You need to first determine if the issue is with the truck, the wires from truck to trailer, or the trailer. Start with truck. Has it ever worked before?
Old 01-22-2021, 05:50 PM
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Originally Posted by SpencerPJ
Are you saying that when your Truck is connected with the trailer, you have no lights? Have you checked the output of your trucks plug? You need to first determine if the issue is with the truck, the wires from truck to trailer, or the trailer. Start with truck. Has it ever worked before?
Thanks for your reply. It is the truck because I've used a Ram Pro Plug Light Circuit Tester Adapter 7 Way Blade & 4 Pin Trailer Wiring Tester and it showed that it wasn't receiving power. The trailer connection was working, but then cut out. And now, I believe my license plate lights fuse also burnt out at the same time.
Old 01-22-2021, 06:04 PM
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Originally Posted by Philly D
Hi All,
I have a 2015 extended cab, v8, F150 and am looking for help on a couple of fuses. I'm looking for info as to which fuse controls the rear license plate lamps?
Also, which fuse controls the running lights for a trailer?
Well don't want to blow a bubble, but these trucks don't rely so much on fuses. Most of the the circuits are fed from the BCM through a FET circuit which if it senses an overload it cuts the power from the circuit. The license plate lights are just part of the parking light circuit, somewhere under the rear of the truck they tie into the rest of the circuits, somewhere a plug under the rear is probably corroded. In these lighting circuits, if the fuse blows, it won't only be the parking/license lights, you will lose quite a few other lights. Being its a 2015, plenty of time for crap to get into one or more of the plugs.
Old 01-22-2021, 06:12 PM
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You might take a peek at 34,35, or 36

https://www.startmycar.com/us/ford/f...o/fusebox/2015

Old 01-22-2021, 06:17 PM
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Rear license plate lamps are controlled and powered by the BCM (Body Control Module). The circuit is protected from over-amperage by the Park lamps FET circuit. BCM FET circuits disconnect power (or ground, depending on the circuit) to the circuit when it senses an over-amperage condition. The FET stays "tripped" until the next ignition cycle when it automatically resets. After a number of "trips" (8 if I remember correctly) the FET circuit will broadcast a DTC (Diagnostic Trouble Code) and remain "tripped" until the circuit problem is repaired and the DTC is cleared. This part of the BCM is powered by the BJB (Battery Junction Box) Fuse-12 (50 A).

Trailer "running" lights are controlled by the BJB Trailer Tow Parking Lamps Relay. That relay gets power from the BJB Fuse-34 (25 A). The relay is switched by the BCM Trailer Tow Park Relay FET.
Old 01-22-2021, 06:46 PM
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Originally Posted by Gordy49913
Well don't want to blow a bubble, but these trucks don't rely so much on fuses. Most of the the circuits are fed from the BCM through a FET circuit which if it senses an overload it cuts the power from the circuit. The license plate lights are just part of the parking light circuit, somewhere under the rear of the truck they tie into the rest of the circuits, somewhere a plug under the rear is probably corroded. In these lighting circuits, if the fuse blows, it won't only be the parking/license lights, you will lose quite a few other lights. Being its a 2015, plenty of time for crap to get into one or more of the plugs.
Thank you for providing me with this info.
Old 01-22-2021, 06:47 PM
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Originally Posted by SpencerPJ
You might take a peek at 34,35, or 36

https://www.startmycar.com/us/ford/f...o/fusebox/2015
Thank you for this info
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Old 01-22-2021, 06:48 PM
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Originally Posted by 52merc
Rear license plate lamps are controlled and powered by the BCM (Body Control Module). The circuit is protected from over-amperage by the Park lamps FET circuit. BCM FET circuits disconnect power (or ground, depending on the circuit) to the circuit when it senses an over-amperage condition. The FET stays "tripped" until the next ignition cycle when it automatically resets. After a number of "trips" (8 if I remember correctly) the FET circuit will broadcast a DTC (Diagnostic Trouble Code) and remain "tripped" until the circuit problem is repaired and the DTC is cleared. This part of the BCM is powered by the BJB (Battery Junction Box) Fuse-12 (50 A).

Trailer "running" lights are controlled by the BJB Trailer Tow Parking Lamps Relay. That relay gets power from the BJB Fuse-34 (25 A). The relay is switched by the BCM Trailer Tow Park Relay FET.
Thank you for this info.
Old 01-22-2021, 06:51 PM
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Originally Posted by Philly D
Thank you for this info.
I should have included that the BJB Trailer Tow Park Lamps Relay is #79.

Good luck finding your problem.


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