I have the 3 Factory Svc manuals for my '97 F250.. Vol 1 Powertrain/Drivetrain. Vol 2 Body/Chassis and Vol 3 Electrical/Vacuum troubleshooting. I'm trying to figure out and locate the 2 relays named "trailer back up lamps relay" and "trailer battery charge relay". My trk has the factory trailer wiring. The electrical diagram manual, pg 95-1 says "For diagnostic info refer to section 02-04 of the svc manual. Section 02 in Vol 1 is Transmission/drivetrain svc, section 02 in the Vol 2 is the cab/box mounting info. There is NO Sec 02-04 dealing with anything electrical. Trying to work with the power distribution box on the LF inner fender leads me to the same dead end. I'd like to lift that thing out and locate wires going into the harness. No service info in the electrical manual, just a reference stating "for diagnostic information refer to section 18-01 in the svc manual. There is no section 18. Vol 2 stops at Section 17. Any ideas out there? What am I missing? Is there more elusive service lit (other than svc bulletins) I'm unaware of? Ford has always had excellent svc info so I find this puzzling. Thanks guys............... Larry

 

Your owners manual will identify the fuses and relays in the PDB under the hood.

 

Maybe these will help.



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Thanks guys, but that's all info I have. The pic I'm posting is of a double relay box, between the power dist box and the firewall. This does not show up on the diagram on the locator page nor in the OM on the fuse relay location pages. I need to access the wires on the bottom of the pwr dist box so looking for the trouble shooting/diagnostic pages alluded to in the electrical manual, exact pages id'd earlier. Thanks

What are the relays for in the plastic box next to the power dist box on the left inner fender?

 

Is the above photo of your truck?

If so the relays inside should be the "trailer back up lamps relay" and "trailer battery charge relay".

 

Yup, that's a pic of my truck. 2 relays there, ones for the back up trailer lights and the other "directs current to charge trailer battery" Is this for a remote battery like you'd find in a camper, or a battery that some folks have mounted on their trailer for a winch? If so then a guy wouldn't need a battery isolater, diode type arrangement to keep the batteries separate but allow for charging? I can find no Ford information on this stuff. Thanks. Thats the reason for this whole post, is wiring the truck for my pick up,pop up camper, I use for ag swap meets, steam threshing shows etc. Thanks guys................... Larry

 

" Is this for a remote battery like you'd find in a camper, or a battery that some folks have mounted on their trailer for a winch?"
Yes it is for both.