Hey all.

I have a stock 1987 Samurai.  I'm having a horrible issue with my charging system and I can't seem to figure it out. 

Couple weeks ago my alternator went out, installed an Autozone unit after fully charging the battery, that night I had no lights and had a dead battery.  Took off the alternator and had it tested at Autozone, tested bad.  I figured oh well bad one, got another, had them test it 3 times before I brought it home, installed it, that night ended up in the same situation.

I'm now on my 5th alternator, they don't even want to do the exchange for me anymore.  I hooked up a voltmeter when I put on the more recent one, no charge.  Took it in to AZ, tested bad, after it had just tested good 3 hours prior at AZ when I picked it up.

Any suggestions on how to diagnose my problem?

Sounds like something is shot in your electrical system.  I would start by checking your wiring, get an electrical diagram and a Ohm Meter (multi-meter) and make sure that all your wires run to where they are supposed to.

Might be an issue with the voltage monitoring circuit or a bad ground.

Well, the plug for the alternator is not there, so I hooked it up with another alternator, and added a ground wire to the third prong of the alternator.  So far so good, but when I first started having this problem, the alternators would stay alive for a day or two then die, so idk so far.  I want to get this fixed so I can do the GM alt mod, I just don't want to be blowing those alternators too.

So just set the meter to ohms and start checking for continuity on each end of where wires in the harness go?

Well, the plug for the alternator is not there, so I hooked it up with another alternator, and added a ground wire to the third prong of the alternator.  So far so good, but when I first started having this problem, the alternators would stay alive for a day or two then die, so idk so far.  I want to get this fixed so I can do the GM alt mod, I just don't want to be blowing those alternators too.

So just set the meter to ohms and start checking for continuity on each end of where wires in the harness go?

Are you running a stock Suzuki alt with non-standard wiring? First would be to make sure you have it hooked up right. Was the factory plug cut or something?

-Eric

If your wiring is missing I would look at a GM Alt conversion kit, then just get a GM One Wire and run it to the battery.  Then your done.

I would buy a new cable to go from the alternator output to the positive of the battery.  The stock cable has a fuseable link in it for overcurrent protection, but if you dont care about that just buy a regular 2 or 4 gauge battery cable.  Make sure you insulate or, better yet, remove your old cable so it can't arc on anything.  If you plan to upgrade your alternator down the road the stock cable is probably not heavy enough so you will need to do this anyway.  The reason I'm suggesting a new cable is because I had a problem with mine.  If you run an alterator w/out being connected to a battery you will fry the voltage regulator real quick.  I burnt through 2 alternators because the cable going to the battery was broken but still stuck together by a thread.  And if you run an aternator when the voltage regulator starts to go it usually starts to put out 16+ volts and will fry your battery pretty quick (which also happened to me).

Something I dont understand is your comment about how you have it wired.  There are only 2 pins that you need to connect, and neither is supposed to be connected to ground. One pin is for the idiot light in the dash and the other pin is connected to 12V thru the ignition.  All you need to connect to make the alternator work is 12V to the IG pin.  http://www.napaonline.com/Search/Detail.aspx?A=RSE2138317_0279576668&An=599001+101987+50069+2069002#
IG= ignition, L=lamp, D=dummy terminal

The charging system is really not that complex - its 3 wires. I can't think of anything beside running an alternator not connected to a battery that would make it fail that quickly. Unless of course you have the IG and L pins swapped, or you are burning out the voltage regulator by connecting the lamp output dirctly to ground.

The stock wiring is all there, just the actual plug was cut off by the PO and female terminals were crimped on in its place.  Why, I do not know.

I have the wires hooked up right, I've checked it over and over again with many different sources to verify this.  The reason I added the ground wire to the third output, "the dummy terminal", is because as far as I can tell, on acks faq it shows this as being ground.

I've driven it a few hundred miles these past two days, no problems charging at all, until a weird occurance tonight.  I took it to the river and we were going down the trails, no big holes (but not tiny ones either ) and my battery light and brake light came on.  Got out and checked voltage with the meter, 12.6 but falling slowly.  So I left the trails, started to head home.  At higher rpms, the dash lights would not be on, and my headlights were as bright as usual.  Come to a stop at a light, the dash lights would come on.  So I figured maybe I was having a low speed charging issue.  Well then I get it home, pull up to a stop in the driveway, no lights.  Headlights are on, normal brightness, no sputters in the motor, etc.  So I check the voltage at the battery, 13.2.       So maybe I just got something wet this time around and once it dried up I was fine?  Idk, seems a bit to lucky if you ask me.

Thanks again for the help so far everyone.

Is everything still charging smoothly after drying it out?