I see on the web that a lot of folks have this overcharging problem but so far none of the tips I've tried have worked, I've pinned out all the wiring, seems fine, all connectors clean and tight, all grounds good, I've swapped the PCM, battery and alternator. Even tried to overlay new wiring and by pass the PCM with an external regulator. I am getting a code 41 for the alternator field control circuit. No fuses are bad, hell I'm stumped.

Does anybody know where I can pick up a factory service manual?

 

There are two small wires on the back of the alternator. One is 12v +, when you turn the key on that wire is 12+ telling the alternator it's time to start charging. The second wire is the control wire. This is the voltage regulator wire. The computer grounds this wire to INCREASE voltage but it does it in a duty cycle. You can measure this with a volt meter but it's better with a lab scope set to read duty cycle. 100% duty cycle is full ground.

Now that I explained how it works I can tell you how to check for the problem. What it sounds like is the control wire is shorted to ground. Figure out which one is key on 12v + and which one is the control wire. Disconnect the wire from the alternator and unplug the computer. Set your volt meter to ohms and check for a short to ground. With one lead hooked to the control wire and one to ground, if you don't see continuity, wiggle and bend the harness to see if there is an intermediate short.

 

Thanks AZ, yeah I've already done that and can't find any short. What surprises me is that I overlaid two new wires and installed a external regulator to bypass the pcm and that was doing the same, with other weird stuff to boot. I'll find it, I hope this weekend.