I am working on Josh's 79 F150 and i am trying to piece together the harness that goes from the firewall to the back of the truck. About where the rear shock bracket is, is where all the cloth wire loom fell apart and i have spaghetti. I have 7 wires i know where 4 go(taillight plug) but not the other 3. And the other 3 all have a single plug on each wire. and my fuel tank sending unit has a 2 pin style connector


These go to the taillight plug
------------------------------
1 Green/red trace (Blinker)
2 Yellow/black trace (blinker)
3 Brown (parking lights)?
4 Black/brown trace(back up)?
-----------------------------
These I have no clue

5 Green/ brown trace
6 Light blue
7 Brown/white trace (heavy gauge)

Any idea guys? I picture is worth a thousand words

 

Somebody? Anybody?

 

I believe the green/brown trace is fuel level. The others, IDK. The fuel level sender will have two wires, one has a bullit connector that plugs into the harness, the other is a short black ground wire that has a ring terminal that grounds to the crossmember in front of the fuel tank.

 

This is the fuel tank wiring harness

 

Hmmm...

Black/ Red should be Back-up
Brown parking lights
Yellow Left Turn
Green Right Turn

Light Blue/ Black connects to Green

My schematic doesn't show brown/ white

Josh

 

Crap. I dont have that. Does anyone know where to find on of those?

 

I got mine from Green Sales but I see LMC has them listed also. Green Sales shows five in stock.

 

Ok. got the fuel tank sending unit pigtail from LMC. I have to spice it into the truck harness

but i still have some questions

The light blue wire runs from the firewall to the back of the truck. There is no plug at the firewall or ar anything at the back to plug it into. Is this some early trailer brake wire?


Next is the heavy brown with a white tracer. Where does that go?


And where is the ground wire for the taillights? Or does it get its ground from the bed bolting to the frame? Taillight harness

 

The tail lights ground to the bed and then the ground goes thru the bolts to the frame. FAIL! That's why it is good to add your own ground strap from the frame to the bed.

 

Good to know. Thanks

 

I really want to know what the blue and brown wires are. The blue wire looks like a factory plug, but the brown is questionable.

I have a 74-78 wiring schematic and a 79 F-Series/ Bronco schematic and neither show those wires "per se'"

I say that because the 79 Bronco schematic does show a BLUE wire tying into the GREEN Left Turn Signal wire at the tail light. However, it doesn't show where the BLUE wire goes.

Josh

 

The brown wire plug is deffinatly factory

 

Brown/White Fuel Selector Solenoid

Blue Auxillary Fuel sender.

On my 1974 F100, the auxillary pigtail comes out about mid-way on the frame about where the fuel line break is. I don't think mine has the pigtail for the solenoid though.

I found the schematic at Fordification:

http://fordification.net/tech/images...aster_3of9.jpg

Josh

 

Thanks Bullit390. that clears it up