I am trying to install a set of OEM fog lights in my 03 F250. I bought a set off of ebay and i also bought a factory switch from an 03 with the fog light option.I talked the seller into cuting the harness and leaving about 6 inches of wire with the switch. I thought i would have to splice it in an run power out to the fog lights. However my factory plug and wires were the same as the fog light switch. So i pluged the fog light switch up and use my test light to find the wire that powers the fog lights( It was Yellow).Now what i need to know is once the wire leaves the switch where does it go.? I've looked eveywhere and cannot find it in the engine compartment. Thanks

 

I have no idea but I can get you back to the top of the list

 

These diagrams are for a 2004. But I suspect the 2003 would be the same. It appears the yellow wire goes to a relay in the Central Junction Box. I can find the fuse shown (F2.43 is fuse #43), but I don't seem to be able to find any information on which relay it is.

 

my 2004 f250 has a connector behind bumper on drivers side i assumed it was for fogs i might be wrong but take a look there note : assume

 

Your owners manual should tell you which relay it is.

 

Thanks guys , but I still can't find the wire once it goes though the firewall. Any thoughts ?Thanks

 

I think it's buried in one of those wrapped up harnesses. I just spliced onto the wire coming off the switch and used one of the customer pass thru access wires to run a new power wire to the fog lights on mine. Life was much more simple that way. My new factory switch works great and I didn't have to start ripping a harness apart.

 

Where can i find the pass thru wires. I read they are wrapped up under the dash , but I can not find them.Thanks

 

It seems like mine were up under the dash above the parking brake. It takes a flashlight and some digging to find them, but the ends of the wires have heat shrink on them so you'll recognize them when you see them.