I know this topic of the ls1 alternator has been beat to death by others on here, but my case seems to be a little different than some others so I thought I'd make my own post..
OK... So my car started a few months ago with 'surging' when I would first fire it up in the morning. It would jump to about 15 or 16 volts, remain there for about 30 seconds, and then return to about 13. Only one time did the car start to die on me when I was driving, other than that it drove fine for months.
Now my more recent problems started after changing the water pump on my bird (not sure if this is related which is why I am posting this). I was driving home about a day or two after changing the pump and I noticed my headlights and gauge lights were more dim than normal. The battery gauge was just slightly under 13 but nothing too bad. Then the next day, I was driving home from work and on the highway my gauges just completely died. It was like the car was off but was still running. Then it just straight up died on me in an intersection. I had to hook it up to another battery (that was brought to me) to get it home. By the time I was home that battery was at 8 volts. So then I knew the alternator wasnt working at all.
I got it home and started doing some testing. I checked my battery with a volt meter and (after charging it) when the car was running it would first surge again to about 16v and then all of the sudden would slowly keep draining into the red zone and then the battery light would come on. I also disconnected the alt from the batt and tested how many volts the alt was putting out alone when the car was running and got a consistent 1.6v which is far less than it should be putting out.
Now to deal with my waterpump conspiracy.. When I changed out one of the pulleys on the pump one of them was misaligned when I put it on, so I'm wondering if driving with an unaligned pulley could have caused a failure? Even after fixing the pulley it is still not working. Also my powersteering pump may have had a small leak, which I'm thinking could have leaked onto the alternator and caused it to fail.
I have also replaced the belt so I know that is good. I'm just not sure what to do. All the other ground wires and such do not have corrosion and everything checks out good. Thinking about doing the truck alternator conversion mentioned on other posts here, but would just like some feedback as to what could be wrong.
ok so I just pulled the alternator. the only other thing I can think to check is the exciter wire with my volt meter while the car is running. if anyone at least could tell me what that should be that would be great.
i put the alternator back on to test the exciter wire volts. was getting a reading of 9.8-10v with the car running and the exciter wire not plugged into the alt. definitely thinking its just a bad alt since the 10v differs a lot from the 1.6v the alt was putting out with the exciter plugged in.
if anyone has any thoughts, please let me know. probably just going to replace the alt tomorrow and see what happens.
Just reading your post and a similar thing happened to me. I'd double and triple check your belt is on right. I did my water pump and I hate to admit it but I put the belt on wrong. It's really easier to do than you'd think. Couple days later my alternator completely died like that. I was checking everything, had the alternator rebuilt at my friends shop, tried running a power wire directly from the pcm and still wouldn't work. My friend looked at the belt again and the damn thing was on wrong. I swear that was the first thing I checked. It happens.
After mine was rebuilt I get the headlights dimming when the air conditoner compressor kicks on and the volts drop down so I may end up doing the KG3 as well. Never had that problem before the rebuild and my guy is one of the best. Been doing it since he was 8.