1986 Sending Unit/Reverse Wiring

[1985 Bronco]

I have a 1986 F250 that someone swapped a Cummins, Dana 60, and ZF5 into. It was originally a 460 truck. My fuel gauge doesn't work, and I went to check if it was a 2 or 4 prong connector last night, and noticed that there were no wires at all going to the sending unit. There were a couple of cut wires going towards the rear of the tank, but I'm assuming those are for the (missing) rear tank.

What are these wires? Reverse lights? The switch has nothing going to it.



Is this for the sending unit? It's up by the firewall.



There's an 86 F150 at the junkyard, will that have the correct harness I need? VIN:1FTEF14N3GPB76980. I have the 2 prong connector on my sending unit.

[mat in tn]

I believe the plug with the four wires is for a neutral safety switch. maybe the truck originally had a c6.

[mat in tn]

im thinking that the green one may have been for something like a choke relay  

[1985 Bronco]

mat in tn wrote

I believe the plug with the four wires is for a neutral safety switch. maybe the truck originally had a c6.

Yes, that's correct. I still have the automatic column in the truck (minus the shift lever).

[mat in tn]

the two clipped wire should track down to the reverse lights getting the proper connector for the trans mounted back up switch should make this easy to do

[ArdWrknTrk]

Every truck has a transmission indicator harness.
Manual trucks are jumpered down there and automatic trucks are jumpered up behind the fuse panel, where the clutch interlock would be.

[Ifitaintbroke]

IMO, based on my experience trying to clean up someone else's hack-job wiring, your best bet will be to run new wires. The fuel gauges are very sensitive to increased resistance. The factory wires are small, and by this time probably have corrosion at several points. There is likely a connector under your brake master cylinder that the yellow/white sender wire goes through. It's also most likely corroded, as it's not water resistant and never was. My suggestion, unless you want to add the rear tank back in, is to find the yellow/white wire in the dash, splice into it, and run a new wire (16ga at least, preferably 14ga) to the sending unit. Then, check the black ground wire coming from the sending unit, and if it has any issues, cut it off and ground it straight to the frame. Problem. Solved. Believe me, I've been trying to band aid this system for 4 years and ended cutting the factory garbage out and replacing it. We're talking about 40 year old wiring here.

EDIT: Didn't read all of the first post. You should be able to get a connector to go on the sending unit. Run a new sender wire and a short ground wire to the frame and you should be good.

[Ifitaintbroke]

And, the connector, if it is found, should plug right into the ZF switch, as it is identical to one on a T-19, and I would assume the other manuals as well.

[ArdWrknTrk]

Yes, the reverse switch plug is the same (and darned expensive!)

But I'm saying that the automatic gear position NSS is jumpered down on the frame rail (at least mine is) and I know mine has always been manual.