I know I'm not the first lost soul on this path, I'm hoping I haven't missed anything obvious. I've got a 02 C5Z 38k miles that threw a Charge System Fault (PCM 1638) last weekend and on my limp home it was showing both low 11.5 normal 13.5 and high 15.5 voltage depending on it's mood. Autozone tester showed bad regulator.

It's the original alternator (PN 10246634 - 110Amp) so I was able to through this forum's resources and found the link to the Valeo M530 regulator.


I installed it yesterday and at first everything seemed great. I was reading 13.8 off the battery. After about 15 minutes the alternator acted like it became disconnected with 12.2 at the battery and threw CSF 1638 again.

I pulled into a gas station, cleared the codes, restarted the car and it was reading 12.5 off the battery for about 30 seconds then it suddenly started charging with 13.5 at the battery.

I then went right to Autozone where I got them to do the little check with their alternator/battery/starter tester. It came back and said the regulator was bad - diodes. I then drove about 30 more minutes highway driving where the car behaved normally.

I then cleaned a few grounds, cleaned battery terminals and stared at the starter and at how I'd have to remove the longtubes to be able to get at the connections on it. I'd say from a visual inspection, they don't look bad.

I then drove another hour (now at night) - it started out fine at 13.5 then 15 minutes in again the alternator seemed to "disconnect" with battery voltage at 12.5 and slowly dropping over the course of the next 25 minutes to about 12.0 where the alternator resumed charging suddenly. No CSF code thrown.

Full cool down (still night), several hours later I drive another hour. Voltage was steady at 13.5 at the battery until I wound it out. Near the top of the rpm's the voltage dipped to 11.9 briefly and threw CSF 1638. This is repeatable. Above 5.5k at WOT it will dip.


It seems very consistent, but still better than the old regulator. I'm thinking next step is maybe another M530 regulator from a different listing? I cant seem to find the slip ring so I've just been cleaning it. If this doesn't work I plan on throwing down for the OE replacement alternator for the 145 Amp - 10305776.

 

I've gone ahead and ordered this (DB Electrical AVA0008 Alternator 145 Amp) Reviews indicate that they've had some luck with getting it working on C5s.

I've also ordered a list of parts from this company in Dallas https://www.maniacelectricmotors.com/501wtral13.html

They have the slip ring among other things. I've ordered the bearing, slip ring, regulator and rectifier. I'm gonna try to rebuild the original one as well.

For the slip ring,
Here's the dimensions in case link ever dies (Slip Ring Valeo Alternator ID 6.60 & 8.85, OD 14.90, Total length 48.30mm)
Replaces / Interchanges - Cargo 230090, 71DV-11, 46018, W162-05

 

Check the connection at the starter solenoid before spending more time messing with the alternator.

 

Yeah I need to drop the exhaust and longtubes to have a hope of reaching it. I'll probably do that while I wait for parts to come in.

What tells me that it likely isn't the issue is the voltage spikes up to 15.5 (at the DIC) that I was getting right after I started getting the first CSF 1638. Never know though.

 

Both of the starter connections were loose to the point where both nuts spun off by hand. That ultimately fixed my problem. However the amazon alternator works as well, and also with the more amps (145A) which is what I'll be running.

I also fully rebuilt my original alternator, I can confirm the parts on that website do fit - slip ring included however the regulator they sent me was the M526 not the M530.

I sourced a new M530 and put it on instead.

 

Really good call!