Has anyone been able to technically determine why a GM OEM c6 145A alternator won't work, or can't be tuned to work with a c5?
Beyond some seemingly boogey man talk about PCM incompatability , there doesn't seem to be a technical or reliable explanation when dealing with OEM or NEW GM parts.
(that is to say, some of the issues seem to be related to sub-par aftermarket or rebuilt parts)

let's get even more specific:
I have a '98 M6 equipped with a factory Valeo 110A alternator....and have a c6Z clutched 145A NEW GM OEM 15841234 alternator accessible

What technical reason exists for them (them = my car and this c6Z alternator) to not get along?

And, to complicate things further, are there "settings" in the newer PCMs that can not be adopted to the (my '98) older PCM to get them to play together?

You could say I'm looking for technical explanations that suggest the problems are insurmoutnable (vs variable but addressable issues like bad grounds, weak batteries, loose belts, poor connections, corrosion, etc. that are known as general trouble makers in c5/c6 electrical systems)

Open to thoughs on this. If I have to be the guinea pig on this, I guess I will... but I'm sure someone has gone thru this and thought about it

 

everything you ever wanted to know at this link

https://www.corvetteforum.com/forums...nd-issues.html

 

I've read that (and dozens of other posts on 145A alternators) and unless you can point out something I missed, it does not address what I'm asking.

 

Half the problem is that there is a forum member who claimed insider information and then posted lots of voodoo BS about how the alternator and PCM were matched until everyone believed it was impossible to use any other alternator. I know you can turn the codes off and/or disable the PCM F/L terminals in the OS and then use any alternator you want. A number of forum members have successfully done this. Unfortunately, they rarely post about it because the fore mentioned forum member would have a hissy fit and post a bunch more BS about how it was impossible and call them names for even suggesting it.

The 2008 C6 alternator connects to the PCM the same way a C5 alternator connects. The 2008 C6 code descriptions match the 2001-2004 C5. I'd give that alternator a good chance of working in a later model C5. I'm not sure about the early model C5 though. I'm also not sure about physical fitment. If the regulator can interchange, then put the early C5 regulator into the C6 alternator and you'll make a compatible 145A alternator for your C5.

If it doesn't work, then the only way to determine why is to put a scope on both and measure the off, starting and running signals and try to determine when C6 deviate from the C5 signals enough to cause the issue. There won't be much that can be done about it though because the internal PCM programming is what causes the codes and that can't be changed without hacking it. Programs like HPTuners are only setup to turn the codes on and off, not adjust the set points that determine the code has occurred.

 

MMM ???....maybe I’ll put my scope on the alternator terminals that are applicable to this and see what I have on my ‘01 !!

 

Great information Thanks very much

 

Hi All,

The 145 amp Denso alternator from RockAuto (with damper pulley) worked on my 2001 Base. Denso PN 2116025. Thanks to this thread for the useful info that guided my decision. I'm sure the AC Delco Gold, PN 10316182 would have also worked, but I didn't want to chance it after everything I've been through with this car.

I just wanted to chime in and hopefully help out anyone who is in the same boat as myself and who stumbled onto this thread. I have a 2001 Base, and as owner #11, I have been busy undoing all of the shoddy work done to this car over the past 2 decades. The last error message I needed to solve was the persistent "Charge System Fault" that this thread addresses. One of the previous owners had clearly cheaped out and bought an incompatible alternator. My battery charged just fine, but every time I would start the car up and the revs went over ~1500 rpm, I was hit with the charge system fault, and no amount of clearing the error message would keep it off the DIC. Simply buying the right part seems to have solved this problem for me.

Edit 2 days later: My hubris strikes again.
Replacing the alternator has fixed the persistent charge system fault. It has been replaced with P1637 & "service vehicle soon" immediately upon startup. Clearing the error message and fault code on DIC does not solve the issue. Fault code immediately reappears. The "Charge System Fault" message may or may not rapidly flash and disappear. It is no longer persistent and does not need manual clearing to go away. I initially assumed these errors were from disconnecting the alternator without disconnecting the battery during the install. I cleared them and moved on after the first start. However, after driving the car today I now realize that these are new errors that are here to stay. I am in the process of diagnosing the issue now. It looks like it could be either loose/corroded connections on the starter & solenoid, a bad PCM, or simply the wrong alternator.

I am waiting for the car to cool down before checking the connections on the starter. I scoped the generator field winding duty cycle monitoring wire and got 30-50% depending on load. It was relatively stable. Not super concerned there. I checked the L terminal with the car running, the harness both unplugged and plugged-in. With the alternator harness connector unplugged and the car running, the "turn-on" pin reads ~10V from the PCM. With the car running and the harness plugged in, back-probing this same wire reads 2.8V. These readings are steady and unchanging. Should the L terminal "generator turn-on" circuit disengage after the field winding is started? This seems like a potential error state to me.

AC on, radio blasting, 50% duty cycle

Idle duty cycle around 30%

2.8V on the field winding circuit. Is this ok?