2H Alternator Questions - Identifying a 24v vs 12v Externally Regulated Alternator (1 Viewer)

[GLTHFJ60]

Good evening gents.

I have an unknown voltage externally regulated alternator on the truck we're putting together. My last question was about drivetrain alignment in the chassis and the prompt response was awesome I'm hoping this question is as easy to answer as the last one.

Based on the 2H FSM, it's clear that we have an externally regulated alternator. I have found the wiring diagrams, and regulator part number, for both 24v and 12v setups, but I cannot find the answer to my current question; how do I tell if an alternator is 12v or 24v?

Truck is 100% 12v, or at least that's what we're wiring it for. If the alternator is 24v then I'm sure I'd fry a 12v regulator if I attempted to wire it up. If the alternator is 12v, then I'm golden and just need to pick up a regulator, then wire it up as per the factory diagrams.

Is there a way to tell if an alt is 12v or 24v either visually or with some testing?

Testing thus far, with B+ terminal disconnected from batteries:
- battery to S terminal results in alternator output of ~23v
- battery to IGN terminal results in ~12v (slightly less than battery voltage)
- battery to L terminal results in no output

Any help is appreciated!!

Reference diagram for terminal labels:

Pictures of the alternator we have:

@ontherxs

 

[bj40green]

I have an unknown voltage externally regulated alternator

Based on the 2H FSM, it's clear that we have an externally regulated alternator

Sorry, but you have an INTERNAL regulated alternator in your truck. The VR is right under that lid that you removed.
You can lift the VR out. Remove the nut on the E terminal. It slides over the E and B terminal.

Each alternator is labeled with a part number and is stamped 12V or 24V.
The same goes for the VR. It's stamped 12V or 24V.

make sure that the wiring is correct.
L = Lamp. This goes to the "no charge indicator" lamp on the dash.
IGN = Ignition. This wire is live with 12V when the key is in the "on" position. It activates the alternator.
S = Sense. This wire detects the voltage in the truck and activates the regulator function. If the VR is a 12V model, the voltage on the +B terminal is around 14.4V at high idle.
If the VR is a 24V model the voltage will go far beyond 14.4V.

It's all explained in my thread: -► https://forum.ih8mud.com/threads/voltage-regulator-int-how-it-works.784192/
and that's where you copied your first picture from. That same picture also states clearly that the VR is inside the square box.

An uncontrolled 12V alternator will go to 24V or so. Thus 12V on the IGN terminal but no voltage on the S terminal.
An uncontrolled 24V alternataor goes easily in the direction of 40V.

Be very, very careful with testing. Start engine while you have a voltmeter hooked up to the alternator +B terminal.
Slowly, V E R Y slowly rev up the rpm's and watch the volt meter. If the voltage goes higher than 14.8V (14.8V is the absolute maximum voltage) it indicates that you have a problem.

Rudi

 

[GLTHFJ60]

Rudi,

I've read a ton of your posts, so thank you for posting up in my thread. I have read the voltage regulator "how it works thread". It's a great reference!

However, reviewing the following pic from the FSM and the following pic from @NQCruiser 's thread, I still think we have an externally regulated alternator. I have the bottom alternator in the following pic, without the silver regulator that spans both studs:

From the 2H/12H-T FSM, page CH-7. w/o IC Regulator means no internal regulator, correct? The 3 pin plug of our alternator is on top of the brush cover, not on the side of what would be the regulator cover.

If I do in fact have an internally regulated alternator, then I should see the proper ~14v (assuming it's a 12v alt) when battery is applied to both IGN and S. I will try that shortly and report back.

 

[GLTHFJ60]

After connecting IGN and S to battery and starting the motor, I measure ~23v at B+. Based on what Rudi tells me above, this means that I've got a 12V alternator, just without a regulator.

Here is another reference pic of what I believe to be a factory internally-regulated 2H style alternator (not what I have):
https://forum.ih8mud.com/threads/alternator-wiring-need-help-with-what-goes-where.481799/

 

[bj40green]

Now that you mention it and after studying the pictures..... YES! you're right! It's a w/o IC regulator model.
Here is what's missing. You didn't mention year and model so I took a 1985 HJ75 for the parts list.

The EPC is not clear on this but you'll need the 27700-15030 VR if the year and model I used are correct.
And this is the set up

Hope this helps.

Rudi

 

[GLTHFJ60]

Rudi,

Yes sir, that is what I found in research too. Thanks for the part number and the diagram! We're going to try an external regulator more easily found in the US first, but if that doesn't work, we'll use the number above.

The 2h came out of a HJ60, although I'm not sure the year. I suspect 85ish through 88, although I don't know for sure. The truck we're installing the motor into is an 86 fj60.

 

[bj40green]

I used that picture from the New Era catalog because it's a very good Japanese brand, the cross references are very reliable, they also give the Nippon Denso number(s) and every VR comes with a picture and a wiring diagram.
I checked for a '85 HJ60 and it's the same VR.

Rudi

 

[TLC Norway]

Sure looks like my old 2h ext regulated 24v alt i had in my 81 and 84 hj 60.
But i have no idea how the 12v looks like.
I vote 24v, sorry...

 

[ontherxs]

Where hooks to what.

Picture of regulator I'm told works.

Pic of old alt connections

 

[GLTHFJ60]

Alright, so forget the factory alternator wiring for a minute.

Going by the team rush image above, and knowing that the 2H alt is on the DS of the vehicle, you should be able to wire the aftermarket regulator pins as such:

I: goes to the black+yellow wire from the fuel cut solenoid plug
A: goes to the B+ terminal of the alternator
S: goes to either N or E of the alternator's plug (I'd start with E)
F: goes to the F terminal of the alternator's plug

I'm using the following pic for the labels for the alternator plug pins:

 

[ontherxs]

Thanks Johnny. I'll get the starter worked out and also get this going.
The fuel cut solenoid plug is this one with the green connector?
View attachment 941080

 

[GLTHFJ60]

Yes sir, two pin green connector.

 

[TLC Norway]

Sounds right to me!

 

[ontherxs]

Ok. I thought I had this correct but something is still not right. I am getting a slightly higher output voltage as it is hooked up now but this morning the primary battery was dead which tells me (I think) the ext. regulator is not turning off even when power is off.

So here is the current set up using the below two pictures.

1) Regulator is ground to chassis
2) "I" is connected to an ignition power source (note: I did not use the the original fuel cut solenoid from the original alt wiring which is on the passenger side of the truck. I used a another switched source (tested) on the driver side of the truck). This may be an issue because I think by doing this I am bypassing the voltage light relay.

2) "A" is connected to the alt. B+ terminal
3) "S" Is jumpered to the "A" terminal of the regulator. I tested with "S" going to the "E" pin of the alternator wiring and then again with "S" going to the "N" pin of the wiring. Neither resulted in an increase in voltage when using an analog multi-meter from the B+ terminal to a ground.

4) "F" is connected to the "F" pin of the alternator wiring. (Side note: I went to tape up the connection. Ignition not on and got a spark when disconnecting and reconnecting the "F" Pin so it has power when the truck is off. I think this is correct because the Battery is directly connected to the ALt and the regulator is grounded so that would make the circuit.) I should have paid more attention in class.

I found a fourth diagram last one below which I need to study more and see if I have everything connected correctly.

In the mean time. Thoughts and suggestions are appreciated.

 

[ontherxs]

Some more diagrams.

So now seeing this an reading another Mustang thread.
"I" should be disconnected its actually for the lamp.
"A" to B+ is correct
"S" should go to "E" pin on alt.
"F" to field


I also think I need to ground the ALT itself which is why the Alt plat is labeled "E"

 

[ontherxs]

Well not fixed. Yet I am stumped.
When "S" from the regulator is hooked to "E" the alt does not charge.

So this is where it was as of last night.
When "S" is jumpered to "A" it charges but also the regulator continues to draw power. Effectively draining the battery when the engine isn't running.
"F" Still from F pin on regulator to F pin (green) on Alt
"E" Pin on alt not used (black wire)
"N" pin on alt not used (blue wire)

So I charged the battery's up to 100% then disconnected the charger and checked after 3 hours and the voltage % based on the chargers reading had dropped to 70%. The regulator is not turning off.

This am with 70% charge and hooked up as listed above with "S" and "A" jumpered together, at high rev. I was getting over 14 volts. The regulator is not regulating its just pushing full charge.

Back to the drawing board.

 

[GLTHFJ60]

I bet these guys would be able to take that alternator and do a one-wire conversion on it with an internal regulator. That would be way cleaner, and easier, than figuring out this aftermarket regulator with the Toyota alt.

http://www.johnnysautoelectricnc.com/

 

[ontherxs]

I'm pulling my hair out on this one.

Here is diagram of how I will try it tonight.

 

[ontherxs]

More input. More research. Here is where we are going tonight.

 

[ontherxs]

Last night I got everything wired per the diagram. The batteries were low at that point to the readings across the start bat was 12.02 when running at fast idle the voltage was climbing but did not reach 14.8V. Tired, I called it a night and charged the batteries off a wall charger back to 100%

This AM, with engine at idle I'm getting 15.02 across the batteries, andat fast idle or under acceleration I am above 17.4V.

Not good.

Two things I thought may be issue. 1) I have 4 gauge ground from the Alt chassis to the battery. This may be redundant and because its a shorter path and bigger gauge it may mean ground is bypassing the VR. 2) I have set the VR up now in three different configurations, I also dropped it and it bounced on the battery creating a quick spark. I may have fried the VR.