I've rewired most of my truck and am almost done. Everything is working except the Temp, Oil, and Fuel Gauges. They are all hooked up to the components correctly, but they all share another wire that I assume is the ground, but I think I must be wrong. The pigtail on the back of the gauge cluster has one wire different from the rest. It is a single core silver wire with a thick rubber Black/Green jacket. I assumed this would be the ground wire, but my gauges still don't work. The Amp meter gauge has a 12V positive, and a 7.5 Volt positive, so now I am thinking the other gauges might have a similar function. On the back of the gauge cluster there is a metal thing by the left turn signal indicator light, it looks like a breaker box. On one side there is a ground for the dash lights, tach, and other things, then there is a 1/4" screw that holds it to the cluster, and it also acts as a ground for the high beam indicator light. The other side is what the strange rubber Black/Green wire hooks to after it runs through the printed circuit board. I am beginning to think this wire should be hooked to a power source coming from the pigtail. I don't have a factory diagram and the Haynes chiltons books just suck. So I'm looking for a confirmation. It's an 86' F-150 300 I6 dual tanks mechanical fuel pump, all emissions stripped.

 

Free diagrams over at garys place 1986 EVTM - Gary's Garagemahal (the Bullnose bible)

 

This one is the specific one you need I think Fuel Tank Selector & Gauges - Gary's Garagemahal (the Bullnose bible)

 

See the "N" with the blue arrow? There is your black/lightgreen wire, it's a power wire. The silver box is the gauge regulator that feeds power to the gauges. Your ammeter should have 12v on both sides of it.

 

Hahaha Franklin you crack me up. When I wrote this thread, I was going to name it "Hey Franklin, Read Here" LOL. I knew you would come through. I'm looking for a way to give you Kudos for being helpful. I thought it should be a power wire, why does Ford keep confusing me? I'm a Dodge guy dang it.

Thank you Kramer as well. Both of you are helpful.

 

Simple, I just need to hook it to power. Sweet, well that sums it up for my wiring. I just need to finish looms and It's ready. I'll snap some photos when I'm done and possible make an updated wiring diagram. It's a nice wiring job. I've had to change a few color codes here and there for lack of having enough, but the fuse panels are on the dash, and the routing of the wiring is better, and there is extra length on all of them. I can pull out components and get my hands all the way around them and never have issues unplugging things. I've done away with most pigtails that do not really need to be there and ridded myself of the dual brake warning system. And am adding a few modern goodies like an extra cig lighter socket for USB chargers. It's coming along sweet. I can remove my dash and vents without removing the harness, It's really very user friendly other than the length of time it took to do it all. I have universal fuse panels that can be changed out easily, and every circuit is on a fuse now so I won't need to trace down fusible links if anything goes wrong. Essentially it's a home made painless wiring kit. I really like it. There are inline splices, but they are all soldered and it's better than have 3 connections per pigtail, less resistance. Also, I've tested the ignition switch and rearranged a few of them to change the power distribution to the fuse panels. There are actually two contacts in there for the starting circuit, so there is no need rfor the dual brake warning system, you simply remove the purple/white wire, then hook up the blue/red wire in it's spot, bam less risk of getting stranded. I could go on all day, but I'll shut up now. I've learned a lot from this, and I highly recommend it. Is till need to get back in there and test the ignition switch to see which contacts are for ACC power, just in case I want it for the stereo. But I'm almost done. Thanks again.