I have a 2017 F250 SD with 6 up fitter switches. My dealership, owners manual, and online I can't find out where to connect the black wire to my accessory light, the red I want to connect with the orange/grey wire.
I have an extra batterie which ford then moves the radiator coolant container to make room for the battery. It blocked the wiring for the switches that come out of the up fitter switch. Ford could not even tell me what the wires were for. I guess they don't get trained from the factory for the new models.
Anyone know what the ground wire looks like or where I ground the black wire.
Thanks

 

Most times you can go to the frame or body, but the body may pose a new challenge now that it is aluminum. Looking at the wiring diagram on the uplifter relay box, it notes a black wire entering that is ground.



Hope that helps...

 

Just forward of the upfitter box is the place Ford wants you to ground the wires. See the black wire that goes to the side wall.
I found the easiest was to detach the upfitter box as shown in pic.

Upfitter box and wires on driver's side inner fender.


Detached upfitter box by unclipping the two tabs that holds it. Black ground wire where wires are grounded.