also looks lke one of those wires on the plug goes back to the ECU on the injection model.

I wouldn't have thought so but if its a thinner gauge of wire then it probably goes to the alternator warning light in the dash

I know this topic is crazy old, but I need to know if those two wires coming from the alt plug can cause the alt to not charge. The alt tested good, but the battery is not charging and im wondering if they matter because they feel loose. Thanks.

Yes they can - one of them supplies power to the voltage regulator and through it, the field coil in the alternator - if there is no field, there will be no output from the alternator.  The second wire connects to the charge indicator.

So could I just run a 12 volt signal to the wire? I have a feeling that the plug is faulty. Which individual slots do what? You could be a real lifesaver, this charging system has been killing me lately! I have put in so many new wires, and tested voltages more time that i can count!!

Look at the plug - does it appear to have locations for three connectors (it should) - hold the plug so the third, empty slot is on top and the wires are towards you.

The wire to the left is the L or lamp terminal
The wire to the right is the IG or ignition terminal
The empty space is the D or dummy terminal.

Connect a battery positive to the output lug (via an ampere meter), connect battery negative to the alternator frame,connect the lamp between IG & L, and connect IG to the battery positive (it's usually connected to the ignition circuit) assuming the alternator is being turned, by an engine or other test source, if the alternator is working, the lamp should go out and the ampere meter should show a charge current.

Well i connected a 12 volt source to the correct plug on the alternator and re-intsalled it. it still doesnt charge!! Can anyone help? I need the suzuki on the road yesterday and this is very disheartening. Any help is appreciated.

have you not done a search for the alt upgrades? I know I did a write up on it... pics too i think, but I could be mistaken... search for it, it will come....

But i dont need an upgrade, I need this one to work. When it was working I had plenty of amps. I just need my stock alt to work, not an upgrade.

i don't screw around with alternators or starter motors anymore.
i buy rebuilt ones with warranty. much easier.
i do admire the desire to repair, however. good luck.
by the way- i use a stock alternator with a 2 battery system(boat switch).

This alt has tested well three separate times, so i know the problem lies in the wiring, I am just no sure how it couldnt be charging with it spinning, a wire running from its output post to the battery + and a 12 volt signal being sent to the correct plug. How could it NOT be charging? Im feeling so lost.

Any guesses guys? I have been searching alternator threads on three forums since the sun went down and still have no idea what I am going to do. the alt tested good, new wire running from charging post to battery positive, all grounds checked and new ones added. And a wire is running from the positive battery post to the ignition plug on the back of the alt. What is wrong? What am i missing? This is such a headache, hopefully someone saves me.

But i dont need an upgrade, I need this one to work. When it was working I had plenty of amps. I just need my stock alt to work, not an upgrade.

i understand that, but the wiring is explained in there... so you would know what goes where and etc... sorry if i came across as an idiot

Is this the original alternator or a replacement?

I've seen replacements that looked identical but needed a third connection (where the dummy terminal is) - after two swaps I ended up taking the car to an auto-electrician and he added a third terminal and spliced into one of the other two wires, but I couldn't tell you which one off the top of my head (and the car is not here for me to check)

This is a junkyard replacement, did other year alts have different plugs on the alternator? Or where they all the same?

As far as I know they're all the same.

I have another question - how do you know it's not charging?  Are you using an ampere meter?  Is your battery discharging?  Are you using the charge light?

Here's why I ask - the replacement that I mentioned was supposedly a remanufactured Suzuki alternator and although it looked identical, bolted in and plugged in - the charge light never went off.  I replaced it with an identical remanufactured unit and had the same problem and that's when I took the vehicle to the auto electrician.

We took the alternator off and tested it on a bench testing fixture and having verified it was working he then added the jumper wire I mentioned and also had to rewire a connection to a carb heater before the charge light would go off.  The charge indicator appears to be off during the day, but is actually glowing very faintly, enough to be seen at night - I have since added an ampere meter to the dash so I can verify that the battery is being charged.