Greetings

1993 F350 dual rear wheels with towing package, I think.

I am trouble shooting the side marker lights on the side flares not working. A visual of the wiring harness reviled nothing. After using Alldata at the library I learned that they are controlled by a relay common to the trailer marker lamps relay. Thankfully I have the owners manual because the under hood fuse/relay box does not ID them. The truck has an additional relay box attached to the above box. This contains two relays that the manual does not ID. Can you tell me what these are for?

Thanks

 

One will be the trailer marker lamps which also control the side marker lamps on duallies and the other one will be reverse lamp relay.

The marker lamp relay will have a brown and brown/white wires going to it, the reverse relay will have black with purple(could be pink) and black with green or red with yellow, should be a black wire to both relays and another color to both that I don't remember.

 

ifrythings

Thanks for your response.

Found out they are back up and aux power. The side marker relay is in the main box.