From what I've found, it may be even easier than that. Ford put the shunt between the alternator and regulator and I think trying to replicate that is what concerns a lot people about the gauge change. But from what I've been reading it will work effectively if the shunt is in between the charging wire and a wire from which you can measure actual battery voltage/amperage, and you don't need to do the deep dive into the alternator harness. If that's true, the shunt can be placed between the black/orange and yellow fusible links. I know Dave is really up on this....I'm curious to hear his opinion.

 

I was going down this road several years ago when I went to install gauges in my idiot-
light-equipped truck. Like a lot of guys, I didn't really look at what I had first, I just went
to plug in the replacement cluster and found that it wouldn't be so easy.

I then got myself a copy of the factory wiring diagrams.

But, trying to decipher that without having the benefit of both types of harnesses spread
out in front of me on the floor was more than I was willing to undertake, I put it on the
back burner and said to myself, "maybe later."

I don't have my wiring diagrams in front of me at the moment but the only thing that
jumps out at me is where it said to disconnect and cap off some wires because they
won't be used. I'm guessing these are the red/green-stripe and green/red-stripe wires that
went to the idiot light in the cluster, I found that those needed to be crossed together in
order for the alternator to charge the battery but I hadn't done any other mods to the
wiring (regulator, etc.) to accommodate that.

I will ping some guys and ask them to take a look at this thread and offer some input,
maybe we can turn it into a HOWTO with pictures.

 

That'll be good to get a few guys looking at this. This is one of those questions that we really should have solved a long time ago....

 

Without a doubt, having more eyes looking at it would be a good thing.
If there is a simpler method, I don't see why the members here wouldn't be able to find it. There's some pretty smart guys around these parts.....

 

A how to with photos would really make turn this into a blessing for me. I really appreciate all the interest and help. I am going to wait for a final method before I start to attempt anything. Thanks again!

 

I myself would not attempt this project if you are a wiring novice. Too many things could go wrong.

I recommend getting the proper main underdash wiring harness and altenator harness from a donor vehicle of the same year, and doing the swap that way if at all possible. It is a lot simpler, and easier to do, and no less time consuming to swap it out, than recircuting another harness to make it work, in my opinion.

With that said, the proper shunt is spoken about earlier, so full altenator charging amps do not go through the .5 amp rated gauge. This is the most important.

Four wires would need to be added.

Two for the tach:
Black/Light Green Dot
Dark Green/Yellow (Dot or stripe)

Two for the Ammeter gauge.
Yellow/Light Green
Red/Orange

As CTBUTIS described: The Red/Light Green wire, and the Light Green/Red wire needs to be connected together directly, and the light green/red wire moved from the Indicator connection on the regulator, to the stator connection. The white/black wire needs to be removed at stator connection and capped.

Here is a factory wiring diagram that shows the different circut paths more closely.

1984-1986 power distribution. 1981-1983 simular

http://i447.photobucket.com/albums/q...scan0002-4.jpg

1984-1986 Charge Start Run: DS-II

http://i447.photobucket.com/albums/q...l/scan0011.jpg

 

I think we're overthinking this (that's a loaded statement). Installing the tach wires and re-pinning the cluster connections are the easy part. The tougher nut to crack is the ammeter wiring, but I think we're more in agreement here than we realize.

I suggest we approach this by looking at removing the idiot light, and adding the ammeter as two seperate functions. After some additional schematic reading, I'm with the same conclusion as CTBUTIS and 81-F-150-Explorer about the idiot light, splicing the red/green and green/red will work. So that takes care of that question.

I think we should look at the ammeter problem separate from what is already in the truck, and ask if we were adding a shunted aftermarket ammeter gauge, how would we approach it? Well, the short answer would be the ammeter is designed to read the difference between alternator and battery load, so we would wire it between the two. That was what drove my detailed wiring post at 2:22 today. I took a long look at 81-F-150-Explorer' wiring schematics which, go figure, are different than mine. But his 84-86 power distribution schematic shows almost exactly what I described in the 2:22 post. Take a look at his diagram and read my description again. If you come to the same conclusion, we've got a four wire solution to this problem.

 

You won't notice much of a difference between a functioning and a non functioning ammeter guage on these trucks...

 

That's very true...it's more of a principle thing.....

 

If you look at the power distribution diagram, it shows both ammeter and idiot light wiring differences, but it's not made all too clear.

From the top where the fuse links hook to the starter solenoid, Circut 291 Black is for the ammeter wiring, and the one right below it Circut 300 Orange and 299 Green is for the idiot lamps. (Ignore the other circut 300 below the first Circut 300.)

If you follow circut 291 back, you can see where Circut 300 and circut 299 eventually tie into it farther back.

This is the area that most concerns me. This is also where the shunt and ammeter wires are as well. If you notice circut 300 and 299 hook directly to the starter solenoid on trucks with idiot lights. These same circuts hook behind the ammeter and ammeter shunt wires on trucks with gauges. I believe this to be essential for proper ammeter wiring and function, as it may bypass the ammeter otherwise if left as is. See if you see the same thing I'm seeing in the diagram. This would cause the ammeter not to read discharge with headlamps or with other fused items in operation from what I see, if it's not addressed in some fashion.

 

At the very top of the schematic I see 655 red/orange tying into 38 black/orange at splice 201. From the splice 201 I see 38 black/orange shunt running into splice 202 where it ties into 37 yellow and 654 yellow green.

 

Follow #37 Yellow down from where it wyes off at #654 Yellow/Green, and it comes to #300 and #299 at splice-211 as I described (not all too well) earlier.

You can also see the and/or symbols { } where the two wiring differences converge together a little farther downstream.

 

Well, as much as I'm enjoying this discussion, the boss says I have to go. I'm pretty sure I've got a spare ammeter, and if I don't I'll pull the one out of my dash and experiment with a couple of different wiring schemes between tomorrow and Monday to see what works. I've also thought of a couple of things 1974F100 can do to help answer some questions since he's got the only actual idiot light setup. I'll ask him via sepcor. Between the two I think we can find a game plan that will work.

 

One of these days, I will make a video of my factory ammeter's operation and give a link to
it here. I guess I'm just lucky in that mine seems to work better than most.

 

I am worried about the trigger wire for charging. I agree with one of the previous posters, the factory ammeter is not the greatest, and that's just icing on the cake to get it wired and working. So I am not going to comment on wiring the ammeter, I believe you guys are covering that pretty well anyway, and it's not necessary to get the truck functioning after the swap. To the original poster, you may just want to hook the wires for the ammeter up to the cluster, and run them down and coil them up and make this a future project after you get the new cluster back in.

When Ford used a "gen" light in the cluster, they used the "i" terminal on the regulator to bring the alternator online when the keyswitch is on. When they used straight power from the keyswitch, they ran this to the "s" terminal of the regulator. This is the big difference between the two clusters and the charging systems.

So when you go to do this, and twist the wires together that used to go to the "gen" light in the cluster, I would go out and take the red/green(or green/red?) off the "i" terminal of the regulator, and move it to the "s" terminal. The wire that was on the "s" terminal can be taped off. If you do not have a electric assist choke, you do not need the "s" wire at all on the alternator.

I am not sure why they wired these two differently at the regulator, except the "i" terminal may backfeed voltage through the keyswitch, and the truck may not cut off when the key is turned off. That's just a guess though.