3G Alternator... yes I know this subject has been beaten to death...

[nick3012]

Hey everyone... I'm trying to do a 3G alternator conversion on my 90 TC Signature. I know this subject has been beaten to death, but info for this TC is just not as prevalent as for the CV and GM. I already have the alternator, I went and got a new one from Advance for a 95 Mustang GT, so it's 130Amp and the small case. So here's where the dilemma comes into play. I planned on just changing the wiring that the car came with for the regulator and running a new output wire from the alternator, but where to? Do I run it to the solenoid or do I run it to the underhood fuse box? And the other question is, what all has to be changed so I can get rid of that old output connector from the 2G? I've spent 4 hours or so searching and reading only to find that the 90 TC is basically alone here in the wiring.


Any help is greatly appreciated!

Thanks!

Nick

[gadget73]

You can run the new charge cable to either location, but I'd probably go for the solenoid if you have the room there.

The 90 TC is a bit odd in that it could have either had the 2g alternator or a 95 amp 3g from the factory. I'm guessing you have already verified that its the 2g with the 2 plugs vs the 3g with one plug and a bolt-on charge cable.

If you follow the cables from the alternator, you should find they go to a connector up on the inner fender area. Through that connector should pass the two black/orange charge cables and the yellow (or yellow/white) battery sense wire. I think you also get the green/red "I" wire that works the idiot light and turns on the alternator. The only one of those you really need is the green/red, but you can keep the yellow one as well if you wish. You may get better charge regulation leaving the battery sense wire in place. Both the green/red and the yellow wire should go to the smaller plug on the voltage regulator. Pull the white/black wire that goes from small connector to large connector out of the bundle down by the alternator, and clip it from the larger plug. You'll need that to connect to the small terminal on the 3g.

The black/orange wires can go away from that bundle. Lop them off at the connector. If you feel some kind of way about it, leave them about an inch long and put some heat shrink tubing over the ends to seal it up. Not totally sure where they go on the other end. It will be a fuse link most likely, but I do not know if that fuse link also powers other things. You'd need an EVTM to refer to. If its on a link that powers other things, you can just leave those wires abandoned in the harness.

At this point you should be left with the small voltage regulator connector with 2 wires going into the car harness and a flying white/black lead. The white/black needs to connect to the little terminal on the 3g. How you want to get it there is your call, but I'd probably either splice it into the proper connector from a donor car, or use a push-on terminal that fits it.

Mount up the 3g and plug the wires in. Run your new heavy charge cable from the output terminal on the back of the 3g over to wherever you're mounting your fuse. Stock value should be 175 amps. Output from the fuse goes to either the starter relay or the fuse box, whichever you can tie things to easier.

[nick3012]

Ah... thank you thank you thank you! I'm going to try and get back into it tonight, if not I will get back into it tomorrow. I'll let you know how it works out! Yeah, it does have the 2G. I've had bad luck with rebuilt 2G alternators... the 5th one just went out and I'm done fighting with them. Yeah it only has the 65amp.

Thanks!

[gadget73]

its a shitty alternator, no doubt about that. I had one burn out on me on the way to a breakfast meet and it died in the middle of an intersection in Philly. I had to get jumped to get it off the road. The harness was cobbled back together enough to get to a friend's house, and I changed it over to a 3g with Scott's advice in his driveway.

[nick3012]

So here is where I'm at. I connected the "S" term of the regulator to the "S" term on the alternator. On the 90, that "S" terminal is a different color, it's brown. I connected the "A" terminal of the regulator to the output connector on the back of the alternator a long with the new output cable running to the stud on the side of fuse block. I started it and had a battery light. With the volt meter with either KOEO or KOER I have around 12.2 volts. I did disconnect the original charge wire with the fusible link in it. I added a 175Amp inline fuse the battery cable where it connects at the fuse block.

I'm at a loss now. Any ideas?


Nick

[mitymerc]

On my 91 gmcp the alternative would not charge w/o the green/red idiot lite wire connected.

I rented a Toro trofeo on my honeymoon, it was a fun car.

[HiFiMerc]

When I disconnected the old charge wire from the starter relay on dad's '91 MGM, the whole car was dead.

[mitymerc]

On my 91 gmcp the alternative would not charge w/o the green/red idiot lite wire connected.

I rented a Toro trofeo on my honeymoon, it was a fun car.

This "smart" phone puts words in my mouth... alternator alternator alternator take that you stupid android.

[miamibob]

This "smart" phone puts words in my mouth... alternator alternator alternator take that you stupid android.

So much for "auto correction"!!!

[nick3012]

On my 91 gmcp the alternative would not charge w/o the green/red idiot lite wire connected.

I rented a Toro trofeo on my honeymoon, it was a fun car.

The green/red wire is still connected in the factory position. I think I might try moving the sense wire back to the factory location and see what happens. The 92 Toro was my first car when I was 16. I still have it and love it. It hasn't moved in 5 or 6 years... but it's in the garage and seems comfortable. I just bought a 90 at the end of last summer that I was going to use as a parts car, but it's too complete to do that to it. Plus it has the VIC in it from the factory along with it's window sticker.

When I disconnected the old charge wire from the starter relay on dad's '91 MGM, the whole car was dead.

I reconnected the original charge wire and it made no difference. On this car, the output wire running from the alt goes to the under hood fuse block which is where it is.

So much for "auto correction"!!!

Plain and simple, auto correction sucks ass.

Did some testing with it today and there is no output from the regulator on the stator connector which makes me think that the regulator is possible bad? I had the alternator tested and it passed the tests - five times. So I'm thinking the alternator isn't bad.

[gadget73]

There really isn't a lot of voltage output from the S terminal on the reg to the stator input on the side of the alternator. i want to say its around 8 volts DC. If it is not making connection, it won't work though. Normally when the alternator is tested, they plug into the voltage regulator and test the whole works at one shot. The brush holder is part of the regulator on these, and without feeding through the reg you have no connection to the alternator field. No field connection = no output.

Check to see if you have +12v from the battery sense connection to ground, and from the charge output stud to ground with the engine not running. If you have nothing there, verify your wiring to the battery.

Red battery light means the I terminal and it's associated wiring is fine.

About all that remains if you have battery voltage at the charge stud and battery sense line is the short loop from regulator over to the stator terminal.

[nick3012]

I did some messing around with things on the car today and did a lot more reading. I went over all the circuits again and after doing all of this the only thing I could come up with was it was a bad alternator. Low and behold, the alternator was bad! I got another one today, threw it on, reconnected everything, started it up, when that light went out I just thought hell yeah! I'm glad to be back in my TC. I can't get over my lights not dimming or the turn signal slowing to a crawl at a stop light. Now I know what to do when converting the new box!

Thanks everyone for everything!

[sly]

[DerekTheGreat]

...I'm glad to be back in my TC. I can't get over my lights not dimming or the turn signal slowing to a crawl at a stop light. Now I know what to do when converting the new box!

Thanks everyone for everything!

That is so annoying! I want to convert my car too but the sticky said something about having to tap a hole out or something IIRC. That and cutting into the factory wiring is holding me back. I wonder if it's just possible to throw a bigger alternator on it instead...

[mitymerc]

That is so annoying! I want to convert my car too but the sticky said something about having to tap a hole out or something IIRC. That and cutting into the factory wiring is holding me back. I wonder if it's just possible to throw a bigger alternator on it instead...

That would Bo ok, IF you don't mind roasting marshmallows over your engine.. LOL. Back around 94_95 I did the alt in my Stang w/the fact wires. It has been parked since 99. No fires yet! Seriously, it is a safety thing to go with correct gauge wiring....