04 GTO Alternator issues x3 failures now

[Rhino1]

I’m running a LS6 with a 04 GTO Alternator (AC Delco part no 92058857 & Mitsubishi Part no A003TA7991), but I have had it failed three times now and want to sense check why its failing.  It’s a two wire alternator, wired up as per the 04 GTO diagram, that also aligns with the RX7 wiring diagram.  I’ve even checked the lamps in the dash, I have a filament lamp on the alternator/charge indicator but a LED on the low oil light.

The first two times it failed I rebuilt it, once with a new regulator & diode pack and the other with a new regulator.  It failed for the 3rd time this weekend, it started with a whining noise from the front of the car that changed with the revs, then the alternator/ charge light came on.  I've stripped the alternator down and there's no obvious signs of failure or overheating.

From my searches this alternator will work with the RX7 wiring and was part of the reason I got this alternator.  The only things I can think of is that the RX7 wiring has 3 lamps in parallel, the alternator charge lamp, the low oil light and the low coolant light, and with me running the low oil light with an LED, this changed the volt drop across it and increased the voltage that the L terminal on the alternator saw, but I’m not fully convinced about this.

My options now are:
1.   Rebuild this alternator with new rectifier & regulator, plus change all of the dash back to lamps.
2.   Buy a new 04 GTO alternator.
3.   Buy a F-body alternator and wire it to the 411 PCM with resistor, but this is a ~100A alternator instead of the GTO 140A rating.
4.   Buy F-Body alternator & modify with self-exciting regulator?

Has anyone had these issue with the 04 GTO alternator before, what was cause and did you find a solution? 

Or are there other options I haven’t considered above?

[digitalsolo]

I had the same issue with my FC and F-Body alternators.

I got annoyed and put a DR44 on it, and ran it is a 1 wire.   Wish I had a better explanation.

[Exidous]

4 pin alternator will have a 470ohm resistor between pin B and switched batter voltage.

Two wire Bosch connector modern alternators like the dr44 will usually need a 128hz pwm input to control voltage.

Then there is the oddball yakazi 2 pin. Needs 12v on sense wire and the resistor above on L. This guy is the Australian GTO cars.

Read deep:
https://speedmaxinnovation.com/blogs/news/almost-all-the-gm-alternator-information-you-could-need

[Rhino1]

Thanks for that link, it’s a very interesting read and opens up some other options such as the later PWM alternators with either the speed max innovation controller or the GM generator battery control module, although I’m not sure if the GM module would work with the 411 PCM I have, but it might not need to.

[Exidous]

The module is meant to go to the PCM only. It's not a requirement if your PCM can output the 128hz at 5v needed. It'll just be voltage feedback rather than current and voltage.

[wompa164]

Are you sure it's an '04? https://speedmaxinnovation.com/blogs/news/almost-all-the-gm-alternator-information-you-could-need

I am deep in research with my '06 GTO alternator and switching over to using PWM.

[Rhino1]

Fairly certain it's an 04 alternator as its has the larger Yazaki connector (same as the FD alternator connector) and the part number corresponds to the 04 GTO.  I've also rebuilt it a few times by replacing the regulator, which was also crossed checked to the Mitsubishi part number.

I'm going to continue looking into the later PWM alternators as it would appear that some of the GMT 800 trucks had the battery control module go straight to the alternator with no connection to the PCM, but I need to check this further.

[Exidous]

That speedmax site sells a controller for the pwm alternators. You just tell them what voltage you want.

[kinger]

I don't have a ECu hook up even though I am also using the 411 PCM.  Mine is set up for a 1 wire hook up, fought issues for a couple years wanted to upgrade to the truck AD44 but the CS130D case is smaller and it fit better around my power steering.  Soooo after looking for better options over 100 amps.  I finally found a tuff stuff alternator part #8242NCP here is the data on it.  I put that in 3 years ago now I think and it's been great, the entire car woke up with the upgrade.  Might be worth a shot. 


Alternator 8242NCP
Part Number: 8242NCP
UPC: 698252012973
Additional Information:
Alternator
175 AMP Upgrade
1-Wire Or OEM Wire
6 Groove Pulley
Aluminum

[Rhino1]

Those Tuff stuff performance alternators do look interesting, does it have any parasitic drain as it would effectively always be on?

Is there any issue with the 6k rpm rev limit on these alternators, such as running a smaller pulley?

[blacksi]

Probably not your issue but tossing it out there.  I had a couple fail due to a small power steering drip...Dripped right into the fins of the alternator.

[Exidous]

Those Tuff stuff performance alternators do look interesting, does it have any parasitic drain as it would effectively always be on?

Is there any issue with the 6k rpm rev limit on these alternators, such as running a smaller pulley?

You'll want the bulb wire on a relay or switched 12v source.

6-7k is fine.