My brother has a 91 sammi and his alt wont charge because there is no charge on the two small wores that plug into the back of the alt. I ran a lead from one of the ON ignition wires an tried to plug it on to the terminals on the back of the alt still no charge. On my sammi the 2 small wires both have 12 volts on them even when un plugged. Does the alternator  need 2 12V charges for it to charge the system?

Should I just try adding another 12v lead to the other terminal?

Try a search for wiring diagram at Ack's FAQ (the link is in my signature, below).

In that search you'll find a great version of the Samurai Wiring Diagram by Corey "Dice" Daniels - it's fourth from the top.

One of those two wires drives the "Battery/Charge" lamp in the dash cluster and the other is a sense wire that connects to the electrical system - I think the ignition circuit - to regulate the amount of charging that the alternator needs to do at any given time.

Use the diagram to determine if the wiring is damaged or has been improperly modified.  This would include anything connected to that circuit, too.  If the wiring is okay, then you probably have a bad alternator.

There is also the possibility that your Fusible link - the white/yellow wire that runs from the alternator to the battery - is open.


I hope that this helps!

I tested for continuity on the fusable link and it is good. The problem is that when the enging is running there is no voltage on either of the 2 smaller wires.

One of those wires feeds power to the alternator's internal regulator, without which there is no field and so no output, the other drives the alternator warning lamp.

does that mean that they should both have 12v on them when un plugged, because if one is to drive the alt lamp it should nt have any voltage on it? I cant tell from the dagram, that ACK directed me to, if they both have 12v on them. My alternator works great and both wires have 12v when unplugged and my brothers have no voltage on either and he gets no charge from his alternator.

Have you checked the fuses?

yes all of the fuses are good.

Hmm - interesting - because according to the diagram, there is one particular fuse that will cause the symptoms you describe.

Anyway - now's the time to get out your ohm meter and trace the wiring back from the alternator connector to the fuse panel and the cluster and see if you have continuity or not.

Whether or not it is supposed to have 12V is not as important as where it get's the 12V from and what else is connected in the circuit.