Fj45 Ammeter Wiring

[stewt]

Hey all,
I’m doing some finishing checks on the wiring diagram I laid out for my 86’ fj45. Everything checks out except the ammeter circuit. I think the black wire splices with the White Blue (WB) to make the red wire. Can someone help me confirm it? I attached a photo of the diagram excerpt and a photo of the wires.

 

[pb4ugo]

IDK, about FJ45 wiring, but have worked on earlier 40 harnesses. I've seen and dealt with wiring harnesses with that kind of damage. The harness should be stripped of all it tape and inspected. That melted white blue wire may have melted adjacent wires that were next to it. That's some major damage. I don't think that red wire is stock and who knows what its connected to and what creative wiring was done. I would strip it and test and repair each wire. Lay it on a 4x8 sheet of something and id and check the circuits. Coolerman's website has wiring diagrams and sells color correct wire.

 

[stewt]

IDK, about FJ45 wiring, but have worked on earlier 40 harnesses. I've seen and dealt with wiring harnesses with that kind of damage. The harness should be stripped of all it tape and inspected. That melted white blue wire may have melted adjacent wires that were next to it. That's some major damage. I don't think that red wire is stock and who knows what its connected to and what creative wiring was done. I would strip it and test and repair each wire. Lay it on a 4x8 sheet of something and id and check the circuits. Coolerman's website has wiring diagrams and sells color correct wire.

I've tested the wires with a multimeter and there is no current.

 

[pb4ugo]

The damage to that harness probably goes deeper into the harness than what you see. The harness should be pulled and all the tape should be removed. When that white/blue wire and the batt wire smoked the insulation it probably smoked deeper in the harness and effected other wires in the bundle that were next to it. I would guess that red wire is connected to a white wire that goes to the batt. This is all a guess at this point. If the red wire does go to the batt the ammeter would have been connected between the white/blue and the red wire(at the po's solder joint). This is just a guess because someone has hacked the harness and there's no way to tell what he did until the wires are exposed along with other damage. Good harnesses are hard to find. It's probably better to fix what you have with color correct wire. The 3rd wire in the solder joint shouldn't be there. I know it sucks to hear.

 

[B y r o n]

I've tested the wires with a multimeter and there is no current.

It's possible that the fusible link has blown and that is why there is no current.

 

[65swb45]

IDK, about FJ45 wiring, but have worked on earlier 40 harnesses. I've seen and dealt with wiring harnesses with that kind of damage. The harness should be stripped of all it tape and inspected. That melted white blue wire may have melted adjacent wires that were next to it. That's some major damage. I don't think that red wire is stock and who knows what its connected to and what creative wiring was done. I would strip it and test and repair each wire. Lay it on a 4x8 sheet of something and id and check the circuits. Coolerman's website has wiring diagrams and sells color correct wire.

This x1000. You really have no choice but to lay out the harness. Anything else is Russian roulette.

Christine

 

[stewt]

It's possible that the fusible link has blown and that is why there is no current.

There actually is no fusible link lol. The venezuleans who built the harness did not add a fusible link and the whole harness short circuited and melted.

 

[stewt]

The damage to that harness probably goes deeper into the harness than what you see. The harness should be pulled and all the tape should be removed. When that white/blue wire and the batt wire smoked the insulation it probably smoked deeper in the harness and effected other wires in the bundle that were next to it. I would guess that red wire is connected to a white wire that goes to the batt. This is all a guess at this point. If the red wire does go to the batt the ammeter would have been connected between the white/blue and the red wire(at the po's solder joint). This is just a guess because someone has hacked the harness and there's no way to tell what he did until the wires are exposed along with other damage. Good harnesses are hard to find. It's probably better to fix what you have with color correct wire. The 3rd wire in the solder joint shouldn't be there. I know it sucks to hear.

Yeah I’ve completely ripped the harness out and mapped it out already. Harness is a electricians nightmare and I’ve ordered wires and such to rebuild it.

 

[pb4ugo]

Your not the 1st to have this type of issue. You might want to check out mad electrical 's website for the tutorials on internally regulated alternators, charging systems, and old charging systems using an ammeter. On both my 40's I no longer use an ammeter style charging system.

 

[South Texas 97]

@Coolerman has original wiring diagrams, which I found to be very useful. Print about 4 or 5 copies in 11x17 format. Some folks laminate one or more copies. I would trace one circuit end to end and then check it off . And then check it again a few days later with a different color pen.
Lay it out on a 4×8 sheet of plywood in roughly the layout you have on the truck. And label all your endpoints. This allows you to see progress. Coolerman also sells a number of connectors and fusible links.
I agree, if possible delete the direct reading Ammeter.

 

[charliemeyer007]

Back in early 90's or so I had the Chilton wiring diagram for my 72 blown up to 2'x3'. On the back I wrote part numbers, torque & tune up specs then had it laminated. I carry it in the rear seat which is folded up almost all the time.

When I redo my wiring I'm going to use like 4 or 5 color of 12 gauge good insulation wires with printed tags at both ends of the wire plus at a bundle junctions. I'll be doing a one wire alternator say 100A with a 8 gauge wire. I just put on my 2/0 battery cables and Elsie cranks over much better than she ever did on 2 gauge with crappy replacement clamps. I will also be running separate grounds to body mounted stuff like lights. Yes I'll be doing a voltage meter -

 

[stewt]

Your not the 1st to have this type of issue. You might want to check out mad electrical 's website for the tutorials on internally regulated alternators, charging systems, and old charging systems using an ammeter. On both my 40's I no longer use an ammeter style charging system.

Do you use a Volt guage and if so, how did you do it?

 

[stewt]

@Coolerman has original wiring diagrams, which I found to be very useful. Print about 4 or 5 copies in 11x17 format. Some folks laminate one or more copies. I would trace one circuit end to end and then check it off . And then check it again a few days later with a different color pen.
Lay it out on a 4×8 sheet of plywood in roughly the layout you have on the truck. And label all your endpoints. This allows you to see progress. Coolerman also sells a number of connectors and fusible links.
I agree, if possible delete the direct reading Ammeter.

Yes! Coolermans website has been extremely helpful in mapping it all out and having references. I'll see how to bypass the ammeter.

 

[pb4ugo]

MadElectrical.com - Mad Enterprises

I've never bought anything from them. I run an sbc, so I use a gm alt. I use the 3 wire setup with an idiot light, with a 6ga alt charge wire to batt. The ammeter won't work with this setup. I bypassed it. I typically can tell the alt is changing by its whine and the light. I think coolerman offers a wiring harness and has an article for Toyota alts with internal regulators , but idk much about that. I run ground straps, engine to frame and body to the frame, batt to the frame and i think body to engine. I use my batt as the junction block. Imo, it's a safer set up. I made fusible links with the proper gauge fusible link wire or @Coolermans sells them along with other vendors.

 

[stewt]

MadElectrical.com - Mad Enterprises

I've never bought anything from them. I run an sbc, so I use a gm alt. I use the 3 wire setup with an idiot light, with a 6ga alt charge wire to batt. The ammeter won't work with this setup. I bypassed it. I typically can tell the alt is changing by its whine and the light. I think coolerman offers a wiring harness and has an article for Toyota alts with internal regulators , but idk much about that. I run ground straps, engine to frame and body to the frame, batt to the frame and i think body to engine. I use my batt as the junction block. Imo, it's a safer set up. I made fusible links with the proper gauge fusible link wire or @Coolermans sells them along with other vendors.

View attachment 3895854

That's some serious stuff. I was thinking of bypassing the ammeter and using a digital battery monitor. 500A Battery Monitor With Shunt - https://www.renogy.com/500a-battery-monitor-with-shunt/ Would that work?

 

[pb4ugo]

There's really not a problem with the ammeter itself, except for the fact the earlier ones are 30 amp and I think the later ones are 50 amp. The problem I have is how the ammeter charging system is wired. I think mad electric has an article on it. Basically the alt/voltage regulator supplies power to the fuse box and the whole wiring harness, and then charges the batt thru a 10 gauge(white)wire to the batt. The ammeter is inline with the white(10ga) wire showing whether it is charging or discharging. I'd prefer not charge the batt by going thru the harness. Damage to the harness like yours, isn't that uncommon.

The internal regulated alt charges the batt, then power is supplied from the batt to the vehicles fuse box. There's no need for the ammeter. I could install a voltmeter, but I don't want the gauge. It's not that involved to wire the alt. It's just 2 or 3 wires.

 

[B y r o n]

There actually is no fusible link lol. The venezuleans who built the harness did not add a fusible link and the whole harness short circuited and melted.

Maybe next time you might want to lead that you're dealing with a South American vehicle.

 

[stewt]

Maybe next time you might want to lead that you're dealing with a South American vehicle.

Sorry, I'm kinda new to forums in general.

 

[pb4ugo]

At this point, It really doesn't make any difference, a fried harness is a fried harness. It just confirms it's most likely been altered and hacked.