I have a 2011 F-250 6.7L Diesel.

I need to locate a 12V+ wire that controls the reverse lights under the dashboard.. I need to tap into it to get a control for a relay that's going to turn on auxiliary lights to make them turn on whenever the truck is put into reverse and the reverse lights come on. Anyone know where I can find this wire, and which wire it is?

 

Tap off the Blue/White wire on the connector for the Body Control Module, located behind the right side kick panel. That wire is HOT in Reverse when the ignition is on.

The other end of that wire comes through one of the firewall connectors up behind the left side of the dash, runs down the driver's side A-pillar, under the seats, than back to the passenger side A-pillar.

 

Is that wire for the auto dimming rear view mirror?

 

No and yes.

No, because that signal feeds into the BCM where it serves as an input the network of microprocessors. That's the only physical wire that changes voltage with the selection of reverse that runs inside the cabin and is in parallel to the actual reversing lamp feed.

Yes because everything else in the vehicle relies on the digital data from the BCM over the network in regards to the status of the reversing lamps. The auto-dim mirror, the cluster display, in-dash A/V, etc all get the status from the network.