nefarius

ok... so this one goes out to all the guru's out there, found nothing in the searches....

I though that i was having the normal internal regulator problem so i went out a bought a new alternator because it just wasn't charging anymore. put the new one on and everything appeared ok. turns out it had been running off the battery for a couple days =-( so anyway i figured that it must be that the new alternator is bad too... turns out not. went to autozone they tested the alternator in the car, showed as bad. took it out and went back, they then did a bench test on it and found that the alternator is good.... so at this point i went back and unplugged everything from the alternator ran a direct ground to the chassis of the alternator and plugged a dmm to the output of the alternator with the car running it shows .1v and if i rev the car up to 4k it shows a little over 1 volt... all the fuseable links are good and seems that it's not a ground problem. anyone have any ideas?

Thanks,
Nefarius

btw, it's an 81 gsl 12a

chedda_j

Im not too sure, but it sounds like a short. I would say make sure that the power wire off the alt is running correctly. I mean the one that runs off the battery.

Im prety sure that the these alternators need a small amount of electricity to start the charging process. So check the wire from the battery. Do the same test and take a wire and run it directly to the power on the alt from the postitive post and see if that helps.

i can give you more information on how this works if you need it, i know my honda alt works that way.

nefarius

yeah that sounds a little weird so i'm gonna need a little more info, wouldn't putting + power to the main output of the alt short out the regulator?

Midwest 7's

iTrader: (4)

did you have the part place guys test your batt. also?

chedda_j

WEll to my understanding the alternators arent self exciting, where some are, but some arent. My honda alt has to have a small amount of electricity running to it from the battery to start the whole process, the small amount of electricity "excites" the alternator and helps it make power. On my car there is a wire that runs directly from the alt to the positive post. That allows the alt to transfer power to the battery, im sure thats the one you are testing. now there should be a ground wire, or a plug with a ground wire on it, or the alt itself grounds itself by the mount. Now if there is a plug that plugs into these alts or onto a post there should be a couple wires. One for your Batery light, and one for the self exciter. Make sure that these arent grounding out, and make sure that fuses are all good.

nefarius

i think the alternator that i have is called the s4 on the boards, it has 3 wires connecting to it. the main power wire, and a harness that looks like a T on it, supposedly one wire is connected to the started while the other is connected to the gauge on the dash. so i dont believe i have a self-exciter line on the alternator but i could be wrong. as for the battery it was also tested and was good.

chedda_j

Well im not too sure what to say, all i could think of its the power wire on the starter is grounding out or loose.

Kim's FB

Sounds like you need a meter and test the wires. On my 85 GS the "T" plug has 2 wires. The top one I think it's black with a white stripe goes to ignition, the bottom one white with black stripe goes to the choke and check relay, then to the idiot light. The big red with white stripe one goes directly to the battery. Check for continuity and check it's voltage.

REVHED

Why did you unplug everything? The connector in the back provides 12v from the ignition switch which powers the exciter. Make sure you are getting 12v to the black wire with the white stripe when the ignitions switched on and plug it back in.

Check that the thick wire also has 12v as it should be connected directly to battery voltage.

There's no need for an extra ground as it's grounded directly to the engine.

Rotaryhaven

iTrader: (17)

I went with a Series 5 alternator and called it a day. Thick wire going to battery like always and from the connector, the thicker wire connected to a constant 12V (sensing wire) and the thinner wire to the alternator warning light. Do a search here. I run all my cars this way with no problems.

nefarius

man you guys are amazing thanks, it always ends up bein something stupid...

nefarius

ok so i figured out the problem, it has to do with the exciter stuff we were talking about... found out that the wire thats supposed to provide the 12 v for a couple seconds at start isnt working correctly. i have to manually provide 12v to it and it works, does anyone have a wiring diagram so i can try and trace the problem back to the cause?