12V power to truck bed

[AndrewF]

I’m looking to add a 12V power supply to my truck bed. Anyone have a good suggestion on where to run the wire in? I don’t want to drill any holes in the steel.  I don’t have the 5th wheel prep package so I could go through that plastic cap that is currently there, but if anyone has a good idea please share.

Also I’d be interested on the underhood side as well for ideas. Whether adding a relay for ignition only, just a fuse so it’s always live, etc. 

[Major Tom]

I ran mine along the driver side frame rail.  Plenty of other wiring harness to zip tie to.  Terminated under the tail light area, you can pull the tail light out for extra working room.  How much power (Amps) are you going to be drawing from the plug in the bed?  The longer the run, the longer (continuous) the current draw, and the lower the voltage drop you can tolerate, the bigger diameter wire/cable you will need.  The dual battery Diesels have several places to pull power from, some using mega fuses if you want to stick with using a fuse.  I haven't looked at the gas battery fuse block.

[rjgvt]

I use the 7 way connector on the left side of the bed for 12v to the LED lights in my ARE cap. Since you don’t have that, I would add that 7 way connector and the harness that connects to the trailer wiring at the back of the truck. 
 

The 7 way connector 12v on my truck is connected to the OEM Aux battery and came that way. 

[rjgvt]

 

[AndrewF]

1 hour ago, Major Tom said:

I ran mine along the driver side frame rail.  Plenty of other wiring harness to zip tie to.  Terminated under the tail light area, you can pull the tail light out for extra working room.  How much power (Amps) are you going to be drawing from the plug in the bed?  The longer the run, the longer (continuous) the current draw, and the lower the voltage drop you can tolerate, the bigger diameter wire/cable you will need.  The dual battery Diesels have several places to pull power from, some using mega fuses if you want to stick with using a fuse.  I haven't looked at the gas battery fuse block.

Thanks, that’s a good idea. Right now only need around 12 amps but I was going to run 10 gauge wire to be safe. 

[AndrewF]

1 hour ago, rjgvt said:

I use the 7 way connector on the left side of the bed for 12v to the LED lights in my ARE cap. Since you don’t have that, I would add that 7 way connector and the harness that connects to the trailer wiring at the back of the truck. 
 

The 7 way connector 12v on my truck is connected to the OEM Aux battery and came that way. 

Does a 7 pin plug/harness there provide power even when a trailer isn’t plugged in? I feel like I’ve read issues on here somewhere of people trying to use the standard 7 pin harness in the bumper for power but the system is too “smart” and it doesn’t work since the computer knows it isn’t actually a trailer.

Maybe it does work if that’s what you use for your cap lights.

Edited April 28, 2025 by AndrewF

[rjgvt]

@AndrewF

 

The 12v is on all of the time at the connector in the bed and the hitch connector. I think I read here somewhere that the Ford is the “smart” connector. 
 

I was unsure if the 12v was connected to the main or aux battery when I got the truck. I disconnected the aux battery and did not have 12v to the hitch connectors. It is fused at the aux battery with a 30A flat fuse. 
 

 

Edited April 28, 2025 by rjgvt

[StingerZ16]

16 hours ago, rjgvt said:

I use the 7 way connector on the left side of the bed for 12v to the LED lights in my ARE cap. Since you don’t have that, I would add that 7 way connector and the harness that connects to the trailer wiring at the back of the truck. 
 

The 7 way connector 12v on my truck is connected to the OEM Aux battery and came that way.

 

This is what I recommend.

You can buy a harness splitter to run up into the bed.

I then just made a 7  pin adapter to 12V always on (2 wire - ground + hot)

I use this to power my DC fridge when traveling.

[AndrewF]

4 hours ago, StingerZ16 said:

 

This is what I recommend.

You can buy a harness splitter to run up into the bed.

I then just made a 7  pin adapter to 12V always on (2 wire - ground + hot)

I use this to power my DC fridge when traveling.

Perfect, thanks. Yeah that is what my first use will be, and its not a bad idea to have the 7 pin plug in the bed anyways so I'll go down that route.

 

Anyone happen to know what the current limit is from that plug?  20A?

[rjgvt]

@AndrewF
 

Mine is fused at 30A at the aux battery. If you only have the main battery, should be a fuse there for the 12v at the hitch connector. 
 

I have a 12v socket I installed in the cab on the lower dash. Socket is rated at 20A, I wired it to the aux battery and fused it at 15A with 12 gauge wire. 

Edited April 28, 2025 by rjgvt

[AndrewF]

I ordered a curt harness/plug but I just realized the truck is partially wired for the gooseneck plug already. There is a harness with extra wire that runs up to the plug location.  Looks to be part number 86520227.

 

Does anyone know what else I need to complete this as “factory”? Do I just need the tow receptacle (I think part 84056018) and then I connect the wires I have into that? Or is there an intermediate adapter/part as well?

 

My harness part number doesn’t line up with the older thread linked earlier, but I’m assuming because I have a 2024 refresh truck and that thread was 2020.

 

Edited May 2, 2025 by AndrewF

[TripleBGM]

I ran a bluetti charger 1 to the bed. Charges fast. Zip tied magnets to the charger. No holes drilled.