Alternator shim

[ArdWrknTrk]

You could disconnect the yellow wire at C610 and bring that directly to battery+ at the starter relay, or the fuseholder.

You see in Gary's illustration that there are two fusible links beyond that.

Once you remove fuse link J and either cut the splice or open connector 610 the ammeter should be completely disconnected.
The black/orange shunt wire is the problem you need to get around.

[FrazerJames]

Thanks! Did I correctly identify fuse j there?

The mystery wire seems to be just red. I’ll clean it up today to be sure.

[ArdWrknTrk]

Edit: In your earlier photo...
You have C610 in your hand.

As you see from the EVTM you have constant power to the cab, wires to and from the ammeter and switched power for the regulator.

The black/orange shunt is spliced between the Fuse link (J) and S202.
If you work strictly from C610 everything from (J) isn't needed -if/until- you decide to convert to a voltmeter.
Then you would need the relay Gary has mocked in to the schematic.

[FrazerJames]

This is fuse J?

[ArdWrknTrk]

Fuse J is connected directly to the starter relay, as shown in the EVTM.
I would say you are looking at (L) or (M) and that your mystery wire must be the red/orange wire of the ammeter.

The only other red wire I can see in that picture is the red/blue trigger wire of the starter relay.

[Gary Lewis]

I agree, that's either L or M.  I know 'cause I cut them out on Big Blue.

And I also agree that the mystery wire is the red/orange wire.  The orange is very hard to detect from red, so they look completely red.

[ArdWrknTrk]

Thanks for the reality check Gary!

I know you have a monitor (or a much better phone) -as well as cataract surgery- to better see these things.

[Gary Lewis]

I'm trying to follow along and add some thoughts here and there, but you guys are going faster than I can keep up.

And, I'm trying to think about what needs to be done on the 3G page as this transpires.  We can't answer every possible question, but we should answer a # of them.  Maybe multiple schematics, including one leaving the shunt in place but with the alternator output moved to the to-be fuse, and one showing the ammeter turned into a voltmeter with the relay added - awa a fuse.  Others?

[FrazerJames]

I’m not seeing anything near the starter relay that looks like a fuse. Maybe that’s where I’m having an issue following. There’s this thing I’m not sure of, but I don’t think it’s a fuse... Maybe I’m wrong?



Here’s a closer look at the wires that the old alternator used to connect to. After cleaning it a bit I’m not seeing orange at all.

[ArdWrknTrk]

My original suggestion was to have a diagram for 1G and another for 2G.
It's really a shame the RJM diagrams are lost.
They were really simple (graphically) and the colors were clear, unlike where you have to keep colors and connectors/splices in mind with the EVTM diagrams.

While I think the EVTM is a great resource, the way that only the wires for whatever circuit are shown, can be misleading when a connector has more wires than you see.
Also, the same connectors can be in multiple places on the page.
I think that confuses some people who don't understand these conventions of the manual.

[ArdWrknTrk]

What you see is a radio noise suppression condenser (or capacitor)

You should have multiple fusible links connected with the battery cable at the starter relay.

[ArdWrknTrk]

That's definitely connector 610.
Maybe you need to look a bit farther up the wire for the orange trace?
Gary is correct when he says it's hard to discern on an old harness.

[FrazerJames]

I think you’re right about the red/orange.

As far as fuses by the battery/starter relay. There are none that I can see anywhere. The only fuses I can find are way downstream (L and M?) as pictured. Otherwise we’re running pure wire at the moment. The only thing that didn’t look stock to me was the battery wire which has been replaced sometime recently. Maybe they removed some fuses? Maybe they already removed the ammeter connection?

[ArdWrknTrk]

Look at the EVTM diagram.
You definitely need more than just the battery cable at the starter relay.
You may not have all those fusible links (like trailer wiring) if your truck wasn't equipped.
But I've never seen a truck with just one (for ammeter)

That's not to say it isn't possible, just that's something entirely new to me.

That's definitely (L) and (M) under your finger in the second pic.

[FrazerJames]

Yeah, the only thing connected at the relay on the positive side was the alternator and the actual battery cable. Other than that L and M, I can’t find any other fuses at all. Do all of the factory fuses look like L and M?

[ArdWrknTrk]

Fusible links do have a rubbery lug attached, like you see with L&M.
They can be replaced with what seems like a simple rubber wire and a crimp connector, but in all cases the wire colour corresponds to their amperage rating (just like regular fuses)

As I said, it may be that your truck only had the one fusible link to the alternator harness, but I just haven't seen that until now.
Are there any other wires nearby that look to have been replaced (like the battery wire has)?

[FrazerJames]

No, everything else looks like straight untouched stock set up. I do have tow wiring in the back. I’ll have to check how that’s run under the truck. I don’t believe it’s factory, but might have been dealer added.

[ArdWrknTrk]

Gary's EVTM page seems to show other fusible links as eec+start and carburetor circuits as being for the 4.9l engine.

I guess it's possible you have neither.
IDK what year his EVTM is....

I don't think it matters what is "stock".
We have to work with what you have "now" at any rate.

The important things in converting the wiring are:
Bring the lt green/red key on power to the 3G regulator plug.
Bring the charge cable to the new fuse, and the new fuse to the battery positive (either at the starter relay, or to the terminal itself)
Bring the thick yellow main cab power wire to either the starter relay battery positive post, or the fused side of the new fuse holder.
Bring the 3G regulator plug yellow/white 'sense' wire to alternator output (somewhere) -i differ in saying this should not be on the far side of the fuse, for reasons already explained-

[FrazerJames]

Got it. Thanks for your help!

Just for safety’s sake, what’s the easiest way to know if the Ammeter is still getting juice? Voltage tester?

[ArdWrknTrk]

If you just leave that plug (C610) disconnected you have both ends of the ammeter wiring right there.