1971 F250 Wiring question

[mulletmobile]

So, there was a little wiring issue with the truck. The PO had an amperes gauge wired in line and a whole bunch of funky wiring spliced in-line so see if you can help me.

There is a connector on the passenger side inner fender. The outside is labeled M8815 and it has a black wire with yellow line, a red wire, and a yellow wire. After a lot of work and diagram tracing I at least have the truck running right. Now the diagrams talk about the red and the yellow being for the DC gauge in the dash. Only problem is this...The red goes into the wiring loom toward the motor, into a fusible link, and then it comes out a yellow wire. So seriously, because I am done chasing wires and trying to decipher diagrams (I have spent over 10 hours reading posts, diagrams and looking at this stuff) where do the red that becomes yellow and the yellow wires out of this connector go to????

Please, I am completely lost and frustrated and need some assistance and thank you in advance!

[Mach428]

What on your truck is not working? If the truck is running and everything is working correctly, leave it alone. If there is some specific problem, advise.

[mulletmobile]

As far as everything working, I am close but my fuel gauge went from reading low to not reading at all, unsure if the DC gauge is working (since they have a very small amount of movement anyhow), no gauge lights and no cigarette lighter. I just wanted to make sure the wiring is good to go with the specific harness (which I can start and drive it so that issue and the neutral safety switch is sorted out) and any other potential issues with the wiring are fixed.

I think I may have one other issue under the dash where the aftermarket A/C unit power unit was plugged in. The PO had it lazily hooked to a green wire with yellow tracer that had a bullet connecter on it. I still have to figure that one out, but I wanted to make sure my under hood issues are are straight too.

[sargentrs]

Go ahead and replace your IPVR (instrument panel voltage regulator). Some gauge cluster problems are symptomatic of a bad IPVR. Cheap and easy to replace and eliminates that variable.

[mulletmobile]

sargentrs,
thanks for the tip on the instrument panel voltage regulator. I will look at that as a next item to replace. There are low miles on this one, but sometimes that is just as bad.

Still no one with advice on the yellow and red wires in the harness with the black/yellow tracer wire? Come on need some help with this one!

Tonight was met with trying to replace plugs at which time I discovered that several boots were disintegrating and one was completely toast. Gapped the plugs and then ran for a set of wires. Only Auto Zone had them in stock so I went with the Gold ones. Word of advice, DO NOT BUY THESE IF YOU HAVE A 360/390! The lengths are all off and the coil wire had 90* ends. Had to run back to the store and got the mid grade ones that looked exactly like the Autolites I just took off only they were black. Truck fired right up and ran smoother. The old plugs were in good shape and had zero signs of fouling. Looked exactly how they are supposed to look.

[sargentrs]

Still no one with advice on the yellow and red wires in the harness with the black/yellow tracer wire? Come on need some help with this one!

I'm thinking it's this circuit that you're referring to. Can you post a photo of the connector in question. A wide shot showing where it's laying on the inner fender with surrounding components and a closer shot showing the connector and wires. I'm having difficulty visualizing it. I'm not that great at reading the fully detailed diagram for the '72 so I'm having trouble locating that circuit at C-8 on the not so detailed diagram.

[mulletmobile]

I will try and get that up tonight. That is the correct area on the diagram. I am just kind of starting to understand it, I just not sure where exactly the wires tie into the system.

[mulletmobile]

thanks for that diagram. I had used that, a full color laminated chart I ordered and a pic I found here where someone had cut open the taped up harness so I could then see the layout.

The wiring is straightened out. The yellow wire itself just needed to be put back in line with the solid black wire from the alternator. The red wire that led into the fusible link and then came out as a yellow wire went to the battery terminal on the solenoid. All wired up, harness is wrapped back up and everything is working great.

[sargentrs]

Congratulations! Glad you got her fixed.

[magic bus]

I just had the same issue with the truck I just bought. PO smoked the harness, it was melted and then botched, hooked up wrong backwards and whatever. That wiring diagram is killer! Got my going as well and the ammeter works.

[sargentrs]