Mystery wires, 1970 F250

[MadMike]

1970 F250 Sport Custom Heavy Duty.

• -Originally a 360/C6 truck w/gauges.
  -Currently has a 460/C6 and a mid 70s steering column.
  -Main harness from solenoid to cab does not appear to be hacked or changed.
  -There is a CD player installed in the dash, sort of, I have yet to look at the wiring.
  -Aftermarket underdash A/C unit installed under dash, Sanden compressor, R-134A system.
  -Original starter solenoid has been replaced before truck was purchased.

There are two wires I can't identify, both come out of the main cab harness and end near the solenoid and battery. I realize these trucks could be optioned in several ways that may not even be fully documented.

First one is what I'm guessing was originally white(looks beige now) with a black stripe. It comes out of the main cab harness and ends with a rectangular rubber block(fuseable link?). I'm assuming that it originally had a ring terminal as its length is perfect for lining up with the solenoid battery terminal. Rubber does not appear to be damaged/burnt. I'm assuming the ring terminal was either cut or broke off. There is no voltage when the truck is OFF/ON/Running.
I've looked at the various schematics here on Fordification, but I have yet to see anything that shows a white w/black wire in that location. Earlier trucks have a white with black wire for the regulator>alternator harness. Not applicable on this truck as the regulator harness uses (I not used due to gauge) Yellow(A), Green w/Red(S), and Orange(F).

Second wire is yellow. It has a 90° rubber coated female spade terminal. It looks like it would be part of the Horn relay harness plug, but the horn relay and harness are intact and functional. All three terminals are in use. This 'spare' terminal is in the same main solenoid to cab harness, this terminal ends near the horn relay. The rubber coating on one side shows it was cut off from something.

Thanks for any help in identifying these two mystery wires.

[basketcase0302]

1970 F250 Sport Custom Heavy Duty.

• -Originally a 360/C6 truck w/gauges.
  -Currently has a 460/C6 and a mid 70s steering column.
  -Main harness from solenoid to cab does not appear to be hacked or changed.
  -There is a CD player installed in the dash, sort of, I have yet to look at the wiring.
  -Aftermarket underdash A/C unit installed under dash, Sanden compressor, R-134A system.
  -Original starter solenoid has been replaced before truck was purchased.

There are two wires I can't identify, both come out of the main cab harness and end near the solenoid and battery. I realize these trucks could be optioned in several ways that may not even be fully documented.

First one is what I'm guessing was originally white(looks beige now) with a black stripe. It comes out of the main cab harness and ends with a rectangular rubber block(fuseable link?). I'm assuming that it originally had a ring terminal as its length is perfect for lining up with the solenoid battery terminal. Rubber does not appear to be damaged/burnt. I'm assuming the ring terminal was either cut or broke off. There is no voltage when the truck is OFF/ON/Running.
I've looked at the various schematics here on Fordification, but I have yet to see anything that shows a white w/black wire in that location. Earlier trucks have a white with black wire for the regulator>alternator harness. Not applicable on this truck as the regulator harness uses (I not used due to gauge) Yellow(A), Green w/Red(S), and Orange(F).

Second wire is yellow. It has a 90° rubber coated female spade terminal. It looks like it would be part of the Horn relay harness plug, but the horn relay and harness are intact and functional. All three terminals are in use. This 'spare' terminal is in the same main solenoid to cab harness, this terminal ends near the horn relay. The rubber coating on one side shows it was cut off from something.

Thanks for any help in identifying these two mystery wires.

Mike,

Try this for the beige with black stripe. It might be the lead that terminates above the passenger side floorboard where the cab light relay normally mounts. Number 526 here shows a black with white stripe in the location your describing. This relay is probably not on your truck yet the wire that would feed the positive to the camper lighting circuit might be what your looking at:





Edit: Did you try to locate it with this?

[MadMike]

Thanks for the input Jeff, but sometimes it's a very, very, very.... very simple(embarrassing) answer.

TL;DR Previous owner bypassed damaged ring terminal with complicated 'fix'.

Due to corrosion and some wire hackage from previous owner(s) I had to clean up the Reg/Alt wire harness first before I addressed these mystery wires properly. Working my way back to the main harness/solenoid I came upon a few well done re-wrappings of the harness. It's amazing what 45+ years of dirt and junk can hide, and what confusion can happen when the schematics are not fully accurate/complete.

Not shown in either schematic correctly are the two connections from the cab to the Reg/Alt harness. W/Ammeter there are two connectors, one is a flat three wire connector that consists of CT37(#8 Black w/Yellow), CT654(#18 Yellow), CT655(#18 Red) and a flat two wire connector that consists of CT904(#18 Green w/Red) and CT6(#14 Yellow w/Blue). These had all been wrapped up together where the terminals for the solenoid come out and where the rest of the Passenger side light wire harness continues forward.

Removing the wrapping exposed more of the two mystery wires. They are both yellow. The beige color is from loss of color and the black stripe is simply from years of the wire rubbing against the black inner fender, no amount of cleaning would remove the black 'stripe'. Removed the rubber block from the 'beige' wire showed a broken ring terminal, then cleaned up the 90° connector and they rung out in continuity. CT33 per the schematics, or CT 460 per the wire chart. Confused I removed the horn relay. It has the rubber plug on it in one piece, cleaned it up and a previous owner when through the tenacious work of putting some kind of rubber butyl compound to make the relay connector look whole. Even used a flag style connector to match the rest. Strange. Removed the bypass wire and goo, installed the old wire and replaced the broken/missing ring connector. Tested all the wires for continuity and any ground faults. Hooked the battery up and tested the horn, it works.

Why someone would go through the trouble of all that work rather than simply crimping on a new ring terminal is beyond me. I'm always amazed at how much work a person will go through to not just simply fix the original component, especially on vehicles.

[basketcase0302]

Wow....yep some nice hacking there. Sounds like he used one of my favs, (when no amount of shrink tube or tape will work):



Glad you got it done. Does the truck still have the ampmeter in it? Most of our bump era trucks ampmeter's have long since quit working.
I ask because it sounds like your found the shunt wiring for the ampmeter.

[MadMike]

Does the truck still have the ampmeter in it? Most of our bump era trucks ampmeter's have long since quit working.
I ask because it sounds like your found the shunt wiring for the ampmeter.

Yup 654/655 are labeled for the ammeter. As for the ammeter. it kinda worked but that was before the wiring was fixed and an appropriate body bonding ground from the battery. Before it swayed about a needle thickness from either side of center. Still need to finish up Alternator installation(missing original large spacer) and verify the alternator itself is fine via the full field test. Ignition switch itself will probably need to be replaced or cleaned. Jiggling the key will net a change of a volt on the S regulator terminal. So I am not sure if the ammeter is dead. Dash still needs to be properly pulled apart and checked for loose/dirty connections.

[basketcase0302]

I believe I have two of those spacers you need here in my for sale parts Steve. Man I remember behind the dash of my 71' before I started I took the air hose with a respirator on and blew out behind it like crazy LOL. Pay close attention to the backside of the fuse panel, (best to unscrew it from the cab and inspect the back side of it as there are usually a few very weak termination point there starting to fail. Sounds like you've came along way on this truck from where you started from.