dtompsett

Ok... hoping someone has experienced this...

I have no rear tail lights or license plate lights. They were working intermittently last week, and now nothing. Dash lights work, front marker lights work, brake lights work. Fuses check out. As far as I can tell from the harness diagrams I can find, power for rear tail lights and front indicators comes from #12 on headlight switch... and I have verified power coming out of the switch. I pulled the dash cover off and accessed the PARK RELAY (triggers to flash lights when you remote lock/unlock), and bypassing the relay triggers all expected lights except for the rear tail/license plate lights.

So then I started at the front, pulled the air filter, and found the harness going to the back. Pop the connectors, I have power on the brake light circuit when the pedal is applied, but no power on the brown wire which I'm expecting is the tail light wire. Not sure if that's connector C148, C149, or C150. Does anyone have a connector diagram for those?

So somewhere between the switch and the connection in the engine bay I have lost a connection. Diagrams I can find show a connection at "main harness, near instrument cluster S224" and a single wire leaving to the front/rear... then a connection at "engine control sensor harness, left side of eng compt S115". It would seem that somewhere between the switch connection and the engine bay, the wires split apart to fronts/rears/trailer... Does anyone know where in the harness this splice connection occurs? Do I just need to start cutting loom at the connector and work my way back to find the splice?

It's also worth noting that there is still power on the trailer wiring circuit... I have power on my 7 pin trailer harness for tail lights.

dtompsett

Ok... some more details for anyone following along...

https://workshop-manuals.com/ford/f_...ns/page_12982/

S115 - Engine control sensor harness, near T/O (takeout) to C148


So... looks like I start cutting loom at the harness under the air filter and trace it back.

kd4gij

Check the plug , drivers side behind spare tire on the frame rail.

dtompsett

Well apparently I'm an idiot.... I was checking the wrong wires in the engine bay.

I found the break where you described, back end by the spare tire. About 3" behind the connector... lights worked while I drove to a buddy's shop, worked until I started messing around under there. Finally tugged in the right spot and saw the wire stretch thin, and then break. Spliced in a new section and we're back on the road... at night.

kd4gij

Glad you got it.