I have a 2004 f350 dually with no rear running lights. I have turn signals and brake lights. I put a new headlight switch checked all my fuses everything looks good but I still can't figure out the problem

 

There are 2 relays in Aux. Relay Box #2, There is a Resistor comes directly from Fuse 2.14 15 Amp. Location Aux. relay box #2 engine compartment LH side fender well back by firewall, Resistor engine compartment LH side next to ground fender well towards front of vehicle. Five pin relays relay #1 pin 4 WH/BK, relay #2 pin 87A RD/YE. Resistor connector C196 pin #1 OG/LG goes to relay #2.

 

I swapped out both of those relays and till no luck

 

ARE you California emissions? 6.0l diesel? Check fuse 2.14 15 amp. Check circuits through connectors starting at main fuse box ye/bk wire, through DRL resistor OG/LG wire, through DRL relay 2 and 1. You might not be hot directly out of main fuse box. Is resistor ok, check ground. Trace your harness. DRL OG/LG wire in your pig tail, BK in pig tail is ground.