I am wanting to completely re-wire everything from the alternator to the fuse box.

 

Any tips on the best way to re-wire it?

 

Well, you could start by telling us "why". Then you could continue, by mentioning the make/model/year/engine/trim (seems the charge wiring changes slightly with year, but put the rest in your signature and people won't keep asking you. Or ignoring you.)

Assuming some good reason (you're the only judge of what "good" is, but how to replace the wiring might depend on what you're trying to accomplish), you could carefully undo the harness, and replace the red-yellow-white, and fat yellow, with the same gauge wire. If you don't want to disassemble your harness, you can just assemble your own charging harness, and run it next to the existing harness. Remember that L (small yellow) does NOT go to the fuse box, it goes to the combination meter.

 

I have a 1986 Toyota 4Runner. I have noticed some cracks in the wiring insulation here and there, so I have decided to re-wire it. Most of the connectors I have been able to get from Eastern Beaver and the connectors I can’t find, I am putting new terminals in them. I am not much for splicing and butt connecting.

 

Then...

 

Hey Rad

I would like to put in a higher amp alternator at some point. I am looking at the LCE 140 amp. They offer an 8 gauge wire with it. Think I would like something bigger than that. Any recommendations?

Since I am removing factory wires, I am thinking of running the S wire directly to the 40 amp link and then from the other side of the 40 amp link to the 80 amp link. That looks like what the splice back to the B wire accomplishes.

My fusible link wire is also needing to be replaced. I am looking at the wire from Summit to splice in. What size would you recommend?

 

If you must upgrade your alternator, my recommendations:
The S wire simply senses battery voltage. Replace wires if desired but keep S, IG and L wires where they are now.
Do not "upgrade" the fusible link. It is there to protect stock wiring downstream of it. Keep all circuits downstream of fusible link stock. If anything happens to after-market circuits, your truck would keep on running.
The new 8-gauge wire is to handle current from alternator to any load, including battery. I recommend to remove stock "B" wire and connect new 8gauge wire directly between alt and battery with proper fusible link between them. I explain why here.
If you keep stock B-wire and connect the new 8-guage wire directly between alt and batt, you would be totally bypassing your protective fuse network. BAD.
Connect a protected fuse block directly to battery. Power ALL after-market circuits from that added fuse block.

 

I am not looking to upgrade my fusible link. It needs to be replaced. It looks halfway shredded. Do I need a 12gauge or 14gauge fusible wire?



I am replacing the factory wires, but putting them back the way they are now. The only thing I am removing is the B wire splice due to B wire being replaced by new 8 gauge, but going straight to the battery.

The S wire runs directly from the alternator to the 40 amp fuse. It will be run the same way.

The split from the B wire that goes to the other side of that 40amp fuse is what I think I can go directly from the 40 amp to the fused side of the 80 amp link and cut out that splice. Similar to the photo above (borrowed from this thread).

 

The best info we have found to determine fusible link size is 4 wire gauges smaller than the wire being protected.
Hard to visualize based on that picture ^^^, but here's exactly how I did my B wire - simpler and more robust.
COMPLETELY removed the stock B wire, except where it connects the S wire to the fuse network.


As built on mine here.

 

Thanks Rad! Did you run your alternator wire directly to the battery or to a distribution fuse box? If to a distru box, do you have any pics? @RAD4Runner

 

Just as my schematic shows, no distribution block in the middle. Stock B wire was completely removed, except the segment that connects S wire to the fuse network.

Replacement B-Wire is below. One end directly to stud terminal of alt3rnator. The other end, actually the end of fusible link wire, directly to battery connector. The battery and alt3rnator basically working directly hand in hand- just like THAT popular GM CS130 system - except for fusible link between them.

I then replaced the stock "B" wire with a single, continuous length of 6-AWG wire from NAPA, parallel crimped to 10-AWG fusible link from Summit Racing, then to battery.



USE PARALLEL CRIMPS, NOT BUTT CONNECTORS, ESPECIALLY FOR POWER CIRCUITS.

I could not find parallel crimp connector for 6AWG and 10AWG combined at reasonable price/quantity, but found out that the crimp barrel of the 6AWG terminal lug fits.



New "B" wire is protected with flex conduit from the alternator "B" post all the way to the battery connector.

 

The factory fusible link wire that goes from the battery to the that bolted on square assembly to the 80amp fuse, did you delete that wire and run the 6awg wire with a new fusible link from the side of the 80amp fuse that the B wire connected?
@RAD4Runner

 

Nope, Stock Fusible link was left alone. It protects stock circuits as usual. Exactly as shown on my schematic.

 

Hi all.
I've got a 1992 4Runner, w/ the 3.0 engine.
It's been overcharging. Thinking that it was probably the internal voltage regulator in the alternator; I had the alternator tested at both O'Reilly's & NAPA.
Both parts stores tell me that there is no problem w/ the alternator or the internal regulator...
So, I understand that the S wire signals the internal regulator in the alternator; of how much current needs to be cranked out.
I'm wondering if there could be something/ conductivity w/ the S wire giving wrong or reduced signal to the internal voltage regulator in the alternator...
What's the best way to check the output voltage signal of the S wire to the internal regulator, and compare it to the battery + top post voltage; to make sure that the regulator is in fact getting the correct signal?

Thanks in advance, J.D.

 

How do you know? What's the voltage on the battery posts when the engine is running (revving)?

You have a pretty good understanding of the S wire. It goes straight from the fuse block to the alternator, so the alternator is setting it's output voltage based on what voltage ends up at the fuse block, after the voltage drop through the high-current A wire. To check the connection of the S wire, you can just back-probe it at the alternator connector. But what you want to find is pretty near to the voltage at the battery posts, so you need to check there first.

 

According to the volt meter on the dash; it's charging as high as 15.5 volts to a little over 16 volts; once the 4Runner is warmed up and cruising along at about 2-3000 RPM's...Whats odd, is that at Idle, it's down around 14 volts; I guess due to the relative speed that the alternator is turning, for one thing...I was thinking that a short to ground in the electrical system could be causing it (there are a few non functioning minor circuits on the vehicle).
I wouldn't think that would be a cause though, to boil the battery, over just a 100 mile trip? The emergency flashers don't work...I did get a circuit tester that plugs into the fuse block to check each circuit for a short to track that down (haven't gotten that far yet; but apparently something is fooling the alternators internal voltage regulator to overcharge.
Right now I'm thinking the S wire has a bad connection somewhere along it or at the fuse block itself...So I thought I'd check that first.
The emergency flashers are not functioning; put a new flasher in it; they still won't flash; possible short to ground; would that be enough voltage draw to fool the regulator to cause such an overcharge issue that it would boil the battery?
Both O'reillys & NAPA when testing the alternator, stated that the alternator & internal regulator was good, could they be wrong?

When the battery decided to boil, it was during the drive home after buying the truck; about 100 miles home. When I left the sellers place, the voltage meter was showing a charge of around 14-14.5 volts. about 80 miles down the freeway; it was showing around 16; I had no idea it had actually boiled the battery until I got home.
When I called the seller on this, he had no idea the truck was doing this; he had not driven the 4Runner for about 6 years...
He is also wheelchair bound, no mechanical knowledge; but I had gotten all repair & maintenance receipts from him when I bought the 4Runner from him.
A mechanic friend of his had replaced the fuel filter in the gas tank; replaced belts, hoses, plugs and had 'tuned it up'... His mechanic buddy said that it was running fine; when they had listed it...

 

I'm not sure you have a short; that should run the battery flat long before you could boil it. But first things first; if the alternator Regulator is good, then the S wire is where I, too, would start. So back-probe it with your multimeter. (No multimeter? No excuse for that! https://www.harborfreight.com/7-func...ter-63759.html ) If the voltage there is more than 1/2 volt different from the battery post, something is very wrong. I don't know if an open in the S wire will cause an overcharge, but high resistance somewhere could.

No. Absolutely not. Impossible.