2004 XC90 2.5 Low Battery Message not charging

[JPoore]

04 XC90 with 181k 2.5 FWD I had the Low Battery message came on when I was in town running errands. I was close enough to the house I figured that I could make it. By this point I have replaced everything on this car except the alternator so I figured that was the problem. I drove by Advanced Auto on the way back to the house and had them check the charging system. Battery was 10.5 volts charging system was NA, my voltage only dropped under load. They advised I get a new alternator. They had one in-stock (Tough One re-manufactured) that was a direct fit so I purchased it and went home an installed it. First time not knowing what to do it took me 4.5 hours not counting the time to go buy a serpentine belt removal tool. Drove back to advanced at 9:30 PM to check to make sure it was charging, and it was not. First thing the next day I drove it to the local reputable Volvo Spec and left it with him the day before Thanksgiving. They called me at 2:30 and said that my new alternator was not working and recommended I buy Bosch only for the Volvo. They put me in-touch with their parts supplier at CarQuest and he was able to get me one by 4:00 . I took the car home removed the new advanced alternator, returned it got my original back and picked up the up the Bosh, this was a rush because is was the eve of Thanksgiving and I needed it fixed ASAP. I spent $ 417.00 & 2.5 hours with some bloody knuckles from that dam serpentine belt. I was feeling proud of my quick work. I then jumped in the car and it started right up no lights. I went back to Advanced to get it load tested,(they were still open a 7:15PM on Thanksgiving eve) the Alternator was not charging. Need less to say I sent an email to the Volvo Spec, I will call them on Monday morning. I did call CarQuest on Saturday they were open and asked if they still had my original alternator if so could they test it. They did and called me back, it was working.

Here are my codes that its pulling
BCM-0057 Power supply Voltage too low
BCM-A031 Comm between control units tolerance control for SAS not run
CCM-0021 Air quality sensor internal fault
CEM-1C02 L-signal too
CEM—1C05 30-power supply signal too low
CEM-6A04 Door locked, right rear Signal too low
DDM-002B mirror motor MC signal too low

I also noticed when driving it home with everything turned off to reduce battery wear, I could hear a slight tick of pop sound coming from behind the dash were the CEM is located. At this point I don’t know what else I can try. I pulled the cover off the windshield wiper motor to inspect the outside of the CEM to look to see if there was water sloshing around in there and it looked pretty normal for a car of this age. Any help is greatly appreciated.

[boosted5cyl]

Man that SUCKS!
If I recall correctly, I believe the alternator often gets replaced without the VRM (voltage regulator module), or whatever the Volvo equivalent is which is often the source of these kind of issues.....
Its an issue across the P2 platform, so if you search any of the P2 boards you might have the answer.