Alternator question (1 Viewer)

[zglad]

I have a gm alternator, i'm not sure which model but it has three wires. One goes to the housing of the alternator, the other two go to a spade plug. The one that goes to the housing is jumpered to one of the plug wires. What does the other wire go to? It is a 75 fj40. I don't have the original wiring harness or factory gages, but the old wire was white and blue. My wiring diagram shows that it goes to an indicator. If that is true, does it need to be connected to anything? Thanks in advance!

Zac

 

[secretagent]

Hey Zach, Welcome. Do a search or go to the tech link. There are a ton of posts regarding this topic. Good luck

 

[theo]

Hey Zach, Welcome. Do a search or go to the tech link. There are a ton of posts regarding this topic. Good luck

This was my first reaction too. Lots of info out there and many, many people with all types of car and truck have done this swap.

But I took a look for my favorite link about this swap and couldn't find it. Spent a half hour on the internet looking for it and struck out.

So I'm pasting it here with no formatting. Hope it's legible. In the meantime, I'll make an html version and ask Woody to put in Tech Links.
cheers,
theo

GM 3-wire alternator into Land Cruiser

I copied the following information from a write-up that used to be on the TLCA Tech Exchange (http://www.tlca.org/trails/techxchg/). I don't see it there anymore but maybe I'm not looking in the right place.


Note: The following instructions, when initially published, had incorrectly switched the connections for the #1 and #2 terminals. This has been corrected. Thanks to Michael Reardon for reporting the inaccuracy, and to Mark Whatley for providing the corrections.

1. Remove the Toyota alternator and position the GM alternator in place. (You may need to use a GM positioning arm). Note that the GM unit has three electrical connection terminals, labeled Bat, #1, and #2.
2. Attach the large 'white with blue stripe' Toyota wire to the Bat terminal of the GM alternator. The other two Toyota wires, 'white with green stripe' and 'white with black stripe', are no longer needed (but see step 5).
3. Make a jumper wire with a ring terminal on one end and a female spade terminal on the other. Use this wire to jump (connect) the Bat and #2 terminals.
4. Disconnect (unplug) the Toyota regulator, which should be on the firewall below the clutch master cylinder. The Toyota regulator will no longer be needed, so you could take it off the vehicle and save a little weight (all 6 ounces).
5. Now comes the tricky part, as you have options. The 'black with yellow stripe' wire at the Toyota regulator connector is an ignition key controlled 'hot' wire coming from the engine fuse in the fuse box. This hot wire must be connected to the GM alternator #1 terminal. The options involve how you want to do this:
a. Run a wire from the 'black with yellow stripe' wire to the #1 terminal.
b. Run a wire from the engine fuse to the #1 terminal.
c. Connect the 'black with yellow stripe' wire to the now unused 'white with green stripe' wire at the regulator connector and then connect the 'white with green stripe' wire at the alternator to the #1 terminal.

Well, that should do it. Happy charging!

Richard Petruilo


I will just add a couple of notes. For those of us with GM HEI, there is an extra step needed to prevent current from feeding backwards into the ignition circuit and supplying power to the distributor, even after turning the key off. (At least, that's what I think is happening. Not too sure, though. Funny feeling to turn the key and have the engine keep running.)

I put an idiot light (charge indicator) inline in the wire that runs to terminal #1 to solve the problem. With a rubber grommet, the light fits nicely in a stock empty hole in the dash of my FJ40. Others have used a diode instead.

Also, your amp meter and related wiring may not designed for high output alternators. (My '76 FJ40 certainly isn't.) I had an episode that brought this home to me. I left my lights on all day and drained my primary battery. I jumped from my secondary battery and started home. The charge rate was so high that I saw a wisp of smoke come out from under the dash and my fusible link got too hot to touch.

I had to disconnect the alternator, drive home on no charge, and use a trickle charger overnight to bring the battery back. I am currently planning an upgrade to shunt most of the current around the amp meter.

Good luck,
Ted Christian

 

[zglad]

Thanks for your help. I actually found the link that you referenced this morning using a search of this site but I could not find it directly from the TLCA site. The link is http://www.tlca.org/trails/techxchg/electric/alt_9511.html

Thanks again.

Zac

 

[theo]

That's the one. Good luck, and thanks for the link. My brain dies a hundred times a day.

 

[ar2stp48]

Pass on the info on that shunt circuit when you upgrade, theo. That would be nice to have to avoid the kind of charging problem you mentioned.
This came along at the right time; having some alt or regulator problems on my 72.

 

[brandon8me]

I had the same problem a couple weeks ago when I decided to overhaul my charging system in my '74. I found alot of helpfull information but most never explained the job completely. I never found that TechExchange article, but the one site I did find to be very helpfull, and mentioned quite a few times on this board was http://www.madelectrical.com/electrical-tech.shtml I liked his idea on remote voltage sensing, and it even listed part numbers for different GM alternators. The other thing the TechExchange article doesn't mention is the higher output of the GM alternator could be too much for the toyota harness and be a potential fire hazard. To avoid this, I ran an 8 guage wire from the BAT terminal on the alternator to a "buss bar" on the firewall just to the right of the heater blower. A 12 guage wire runs back from the buss bar to terminal #2 on the alternator (this is the remote votage sensing circut, instead of
using the jumper wire from #2 to BAT) I used the old voltage regulator connector to connect a new wire from the ingnition
to terminal #1 on the alternator. I also had to add a diode (like others have mentioned) to make sure the engine turned off.
I then routed a 12guage wire with fusable link to the starter. The starter directly connects to the battery so this completes the charging circut. To get power back into the cab, I used the original charging wire that connected to the battery and
wired it with another fusable link the buss bar. The only drawback that this caused is now my ampmeter no longer displays
a charging state, but it will let you know your drawing power when lights/heater are on. On the plus side I didn't have
to pull out the guage cluster to bypass the ampmeter. I plan on rewireing and using new guages in the future so at that
point I'll switch over to a voltmeter and probably replace the diode with an led for a chage warning light.

I took pictures of the whole process, including fabbing a new mount for the alternator, when I find time I'd like to do a write up on it.

cheers,
-Brandon

 

[zglad]

Theo, if I connect a indicator light in line from the fuse box to the #1 spade on the alternator, won't it always be on when the engine is running? I guess I don't get it.

Zac

 

[brandon8me]

No. When the alternator is not producing a charge the #1 terminal is grounded, thus closing the circut from the ignition
line, and powering the light. When the alternator is running the #1 terminal is disconnected from ground
so the light goes out.

good luck,
-b

 

[zglad]

Okay guys, I have the thing running, but when I turned off the key, the engine kept running. I disconnected the battery and that was no help. I eventually had to put it in gear and dump the clutch to kill it. I have a HEI system, and I put an inline LED light in my dash on the engine fuse to the #1 plug on the alternator. Why didn't this work? Any suggestions?

 

[theo]

I put an inline LED light in my dash on the engine fuse to the #1 plug on the alternator.

LEDs are a different critter than filament bulbs. I don't know much about them. But they are diodes, so maybe you just have it wired backwards. Try swapping the leads??

Also, you may need a resistor in series with it?


Here are a couple of sites:
LED Museum
LED series resistance calculator

 

[zglad]

I tried switching the leads on the LED, no dice. I then installed a regular filiment bulb, switched the leads and it still does not turn off. When I turn the key off, the light turns on. Does that mean anything? What is my next step?

 

[theo]

Getting trickier now. You're going to exhaust my "expertise" in about 2 seconds.

I had a similar problem at one point. I have a working system with a Delco 12si that I rebuilt. It has new triode, regulator, brushes, and a higher output stator. I swapped in a different 12si that I also refurbished and had a problem like yours. Can't remember if the light came on when I turned the key off, but I know the engine kept running.

I didn't replace the regulator in that second unit because it tested OK. I suspect it needs a new one, but I'm not sure. I put my "good" alternator back in and set the other one aside.

I would first make sure the wire that you put the light bulb in is the same wire that runs to terminal #1, and that it is hot and cold with the key on and off. Seem like dumb suggestions, but you don't have original wiring. Could be a mixup there??

If that checks out, then I guess I'd take the alternator apart and get the regulator tested, or just put a new one in. I think I pay ~$3 for them. For another couple bucks you can get new brushes. Test the triode at the same time.

Not sure what else. Could use some help, fellas!

ps - you can kill the engine by pulling the hot lead off the distributor if it suits you better.

 

[brandon8me]

Hmm, if the light is illuminated when the ignition is off I would suspect it's connected to an always
hot circut, and causing the alternator to continue generating current.

I would double check to make sure the circut your connecting to is ONLY on when the ignition is on.
You could leave the light connected but I would install a diode too.

I think the light is supposed to draw enough current to disable the alternator but I wouldn't trust
it on it's own. And yes an led would work but this usually requires a resistor like Theo mentioned and
I think it would require a little more complicated hookup...

Get a 1 watt diode from Radio Shack. It should be a small black cylinder with wires out each end and
a gray or colored stripe on one end kinda like this: -----[__|]-----

To hook it up correctly the side with the stripe (negative or cathode) should connect up to the #1 terminal at
the alternator. If this is connected backwards it would probably not allow the alternator to turn on and
you would be running off the battery. [+ from ignition] -----[__|]----- [to alternator]

If you use the LED the anode (positive) is the longer lead and the cathode (negative) is the shorter lead.
So in this case the shorter lead should be the side connected to the terminal on the alternator.

When I did my charging system, I put the diode in between a pair of crimp connectors to seal it up and protect
it.

Hope this helps!
-Brandon

 

[zglad]

Thanks guys, I'll check it out tonight. I hope the diode fixes it because my alternator is brand new. Also, should my alternator be grounded with any external wires or does it just ground through the block?

 

[zglad]

Just checked, the wire is only hot when the key is on. I'm sure it is running to the #1 terminal. I'll try the diode tomorrow.

 

[zglad]

I've got another thought. Does anything connect to the R terminal of my starter? I have the power to the coil connected directly from the + lead from the battery. Is that wrong. My thoughts are if I power the coil directly from a fuse that is only hot when the key is ON, the engine will shut off when I turn the key off. Is that right, or will I be in the same boat? Sorry for the numerous posts on the same topic.

 

[Planet_X]

This may or not help as my memory is fuzzy, but thought I would through this out there.


Here is a photo of a sort've complicated circuit I ran for my alternator delco cs 144. The diode is the little black thing that looks like a mini fuse (will fit in mini-fuse holders) and the tubular black thing that has the two wires on the end is the resistor.
The resistor takes the place of the electrical resistance that a dash charging sytem bulbs filment would provide. Also some oem installations used a 'special' wire that was a resistance wire- which again does the same thing as the bulbs filment- reduces voltage to the alternators excite wire (?) guessing here-so double check.

The diode acts as a check valve- electricity will only flow one direction, in my case I am running an aftermarket ignition box, which could send voltage to the alternators regulators keeping the thing engergized 'run-on. But with the diode there is no 'backflow' of electricity.
Waytek sells these 'mini-fuse type diodes if they are something that might float your boat, but other types as mentioned will do the trick as well.
Basic this complicated setup is '1' wire. So a wire coming from the fuse panel goes into the diode and then into the resistor than to the alternator. So once the vehicle is shut off because of the diode no residual current from the alternator can flow from the alternator back through the run circuit energizing the jacobs box or in your case the HEI.
Oh, the R terminal is to bypass the ballast resistor when starting, but I dont know if you have a ballast resistor with Hei. Again take this with a grain of salt as it has been awhile since I screwed with the electrics
This is just off the top of my head but it is something like that...I think.

 

[theo]

I have the power to the coil connected directly from the + lead from the battery. Is that wrong.

Hell yes it's wrong! What the hell do you think we've been tellin' ya boy? Goshdammit, son, git yerself a wiring diagram or sum such an' do er up right!
Seriously, you shut the engine off by cutting off power to the coil. Tech Links has wiring diagrams. The coil + wire must be switched!

And to think we put all this effort into curing a bellyache for a guy, when what really happened was he shot himself in the foot!

 

[theo]

zglad, did you get it working?