New alternator not charging.

[Chazzo]

Hey All,

I installed a AC Delco reman alternator on my 2000 V6 manual LS over the summer (July) . I was driving last weekend when ABS light, air bag light came on dash and started losing power. I pulled over and checked FORSCAN for codes multiple codes for modules and multiple low voltage codes. Shut the car off but it would not restart. I installed a new battery to get it home suspecting a charging issue. Hooked up multimeter while running was getting 11.63-12.1 volts at battery. I installed another alternator yesterday and still charging at same voltage. The car has no dash lights and appears to run fine. I have gone through all fuses and fusible links in all 3 fuse panels including the whopper fuse on the back of the battery fuse panel in trunk. I have tested continuity from the terminal on the alternator to battery terminal and get continuity.
Am I missing something?
Is there a fusible link somewhere not in a panel?
I have heard bad PCM can cause issues but that doesn't quite make sense?
Any help would be appreciated?
FYI car is well maintained I do ALL preventative maintenance and do not thrash on car.
I did install an electric fan using aftermarket fan controller over the summer and have small amp/system in it.

 

[AmsterDutch]

That may be the problem ....you might need a more powerful generator for the electric fan due to replacing hydraulic power fan

 

[Chazzo]

I don't disagree that the fan could have killed the old alternator. But the alternator I put on Saturday should still be producing over 14 volts until the fan load kills it. That is the problem at the moment.

 

[04_Sport_LS]

The PCM regulates the voltage of the alternator. So you either have a PCM issue, or possibly a wiring harness issue, (if ALL fuses check out).

Alternator voltage should always be 1.5 volts higher than the battery voltage.

Try disconnecting the cooling fan and the system, and see if the voltage increases.

If not... then it is possible that the extra electrical load damaged the alternator or PCM.

 

[joegr]

It's well known that those aftermarket alternators do not work correctly on the 1st gen LS. For whatever reason, they never realized that the 1st gen LS used a non-standard alternator control scheme.

 

[AmsterDutch]

The PCM regulates the voltage of the alternator. So you either have a PCM issue, or possibly a wiring harness issue, (if ALL fuses check out).

Alternator voltage should always be 1.5 volts higher than the battery voltage.

Try disconnecting the cooling fan and the system, and see if the voltage increases.

If not... then it is possible that the extra electrical load damaged the alternator or PCM.

Thanks for chiming in on this subject ...that is a good trouble shooting process

 

[milehighmikey]

Go Motorcraft or Go home (on a tow truck).

 

[oddball]

I had good luck with Napa alternators, YMMV. Joe's note is absolutely correct. These alternators are entirely reliant on the PCM to regulate output - they don't do anything on their own. And the aftermarket regulator units on the alternator are junk, so it's not surprising to have early failures.

 

[DaleGrib]

I used a Bosch alternator on the Gen 1 and didn't have any issues. But I know many of the aftermarkets won't work. Is it possible Bosch made the alternator for the Gen 1 LS? The only reason I went with Bosch when I had my Gen 1 was cause it was a brand new alternator vs all I could find at the time was rebuilt OEM and not new. Also when I bought it on amazon it had a price glitch and it cost me only $101 for a brand new alternator! https://www.amazon.com/gp/product/B000BZJP8C/ Bosch AL7595N is the one I used if that helps.