A looong time ago, I bought one of those 140 amp 1 wire Tuff Stuff alternators. Now that I have the car running I think that I am running into a charging problem. I went to start the car yesterday and the battery was dead(It's an Optima red top that is only 1 month old!) I had to jump start the car. As I was looking at the alternator, I can see that it has a place to put a plug/connector on the side, very similar to a factory alternator does. The only wire that I have connected is the 10 gauge wire from the back of the altenator + post to the juction block by the battery. Should I get a factory connector and run extra wires? I want this to be a reliable setup, I just can't belive that the battery drained so fast. And no, I didn't leave any lights on. Any info on this would be greatly appreciated. Here are a few pics...

 

Here is a pic of the rear post on the alt....

 

And my limit of 3. This pic is of the actual connector. So, is it OK to leave this connector empty or should I rig up something to go in there?

 

Well, that connector there is for the voltage regulator on the alternator. One of the wires going to it is a fusible link from the starter solenoid and the other one goes to the fuse panel. BTW, nice looking setup from what I can see in the pictures.

 

is it making voltage?
if it is, leave it alone.


one wire alternators may have that plug still....... but it doesnt use it. the regulator is self exciting.

 

Well, that's what I need to figure out. I don't have any access to testing equipment, I am just *assuming* that it isn't because of the battery going dead in such a short time frame. I will have to find a way to hook up something and check it out before I go tearing into it. Oh and Trickster, thanks for the compliment! I'm using the March Performance Serpentine Belt conversion setup. I like it alot. Really cleans up the engine compartment. You can never go wrong with polished aluminum parts!!!

 

goto walmart, radio shack, a parts store, hardware store, ect.... and get a multimeter.

best $12 you'll ever spend (unless you goto radio shack.. then its $50 + a $20 battery... lol)


set it to DC 20volt scale and start the car.. touch it to the battery.

if it reads 13.7 -14.5 V you're cool..... if it doesnt, dont giveup yet... rev the motor for a sec so the alternator spins faster.. that should excite the regulator.. then check the voltage again..

 

You do have a one wire alternator. The one wire doesn't refer to the battery wire, it refers to the number of wires that come out of that terminal. In this case, there should be four terminals inside the connector. The only one used is terminal "S". This runs to a fusible link and further down to the battery terminal on the starter. This is the voltage sensing circuit for the voltage regulator inside the alternator. Without this wire, or with a blown fusible link, the alternator will not charge the battery.

 

Firechicken: Thanks for the info! I have yet to test the voltage coming out of the alternator yet, but what you say does make sense. In the case that you pointed out, you are correct that there are 4 terminals in that connector. So with that being the case, which one of those terminals is the one for the voltage regualtor? If I am not mistaken, I think that three of the terminal blades are small and the fourth one is a little bit thicker. I assume that that is the one for the voltage regualtor??

 

All I can tell you is it would be terminal "S". Each terminal should be maked in tiny barely legible letters that are probably on the side you can't see without taking the alternator out. If you can wait until tomorrow, I'll go out and check mine to see which of the four it should be. For some reason, I want to say it's one of the middle two, but I'm not sure without checking.

 

Well, let me check mine really quick and see if it has any of those letter markings on it.....

Nope, nothing. No letter markings on either the case or on the plastic part of the connector. This makes things interesting...

 

get a meter.

check.





that is the ONLY way you're going to accomplish anything.

 

I agree 100%, just need to go out and get a meter. It is a good thing to know about the S terminal thing though, if for some reason it won't charge, I have some direction to go in.

 

A meter is always handy to have when working with electrical circuits, but will tell you nothing if everything isn't wired up first.

The large terminal is the sensing circuit, terminal "S". This should be wired through a fusible link to the battery terminal on the starter. This allows the voltage regulator to monitor battery voltage and adjust the generator output accordingly. This should solve your charging problem since the regulator is self exciting on a one-wire alternator.

In the event this doesn't solve your problem, you may need to use a second wire. GM uses a second wire to excite the regulator. This wire comes from terminal "F", the terminal next to terminal "S". GM wires this to the 20-amp Fan fuse, but any 20-amp fused hot-in-run circuit will work.

 

I have the same exact problem right now. I have the old style alt. and this same exact March pulley setup. Now, I can use my old alt. but it looks like sh_it. So I purchased a newer style alt. so that I can use the turnbuckle mount instead of the ugly 1986 bracket. So my question is this, can I just wire up my existing alt. harness (2 wire-red and brown) to this plug I just bought at Pep-boys to fit this style of alt.? Only problem is that this plug is a three wire just like the newer ones, maybe 1988-up. Bigger guage red wire and a black and brown wire. Can I just wire it up and cap off the one I do not use or do I need to wire that up to something? I would assume no since my car does not require three wires now. I just want to make sure it will work. thanks

 

bump

 

UPDATE!!!!

I charged the battery at work all day on a low charge. I got it home and installed it just a few minutes ago. I bought a digital multi meter from Radio Shack per your guys' advise. The battery by itself had 12.5V. After I got the engine started up, I revved it up a few times to simulate the RPM's needed to excite the regulator. Anyway, after the revs, I checked my voltage at the battery, and only found 13.0V. I do not think that there is sufficient voltage to keep the system charged, hence the reason why it is always needing a jump start. So now I guess that I need to look into finding a connector with the wiring that goes from the alternator to keep the charging voltages up. Anyone got any ideas?

 

I found my plug at pep boys. My problem is that my stock harness is a two wire setup and this alternator takes a three wire plug. Now with your setup, do you even have an existing harness for an alternator? Sorry for the hijack but our problems are very closely related. Need more help though. Plus I have not gotten out there to just test it out and see if it will run on the two wires I have!

 

86IROCNJ: The main problem that I am running into is the fact that the car was originally a V6. I knew that I was going to run a carb'd V8, and the ECM and all the related wiring would not be needed so I got rid of all of it. Unfortunately, I did not think about the alternator because I was set on using a 1 wire alternator and thought that all I needed was the 1 wire from the back of the alternator to the battery positive terminal. I am just going to have to go to the junkyard and find a car that still has the alternator wiring, trace where all the wires go, and then add it into my system and check to see if it all works.

 

I'm having a similar issue with a TPI conversion I am now doing. I bought the harness off Ebay and it is about 99% complete. However, it still has a couple of cut wires. Several of them I can only conclude are for the Alt, as there is currently no alt. connection. I have connected the wire from the battery to the rear of the alt. and I purchased the pigtail at autozone that "SHOULD" work. Now, I have 3 wires to locate. I have located one that should be the constant pos. wire and the wiring diagram calls for a brown AND a brown or tan wire to complete the connection. unfortunately, the wires on the pigtail are red, brown and black. Any input would be helpful..