I've just put up a second fight with this on my '08 TSX.
My week went as follows:
Monday morning 1/2 through my commute:
1) Check Charging System Light
Head home at lunch to avoid breakdown in traffic. Car cuts all power on the highway. Restarted OK and got within 5blocks of home before cutting completely, would not start. Towed home (AMA thank god).
2) Replace alternator with new OEM Tuesday
Drive to work Wednesday, with intention of taking to Acura Mechanic friend after work for an A3 service & investigation, 2min away from work:
3) Check Charging System light
4) Take to Acura, Alternator and Battery showing problems with GR-8 test
5) Replace battery since Alt is new (no replacement/warranty alt on hand)
Driving home, within 500m of Acura
6) Check charging system light
7) Service % Drops to 0 even though it was reset while at Acura.
Drive home with no issues, while showing CCS light
8) Warranty Alternator and replace with new OEM last night, quick drive (15min) shows no lights
Drive kid to daycare this morning, on the way home from Coffee stop
9) Check charging system light.
Get home, turn off/on
10) Emissions light, CCS light, service % down to 0 (repeated 3-4 times)
Acura friend and his coworkers stumped, none have heard of this happening
BT module was disabled a few months ago
I took the following steps and haven't had a light for the rest of the day.
Checked voltage and new alt with battery charger, battery was reading 14.3V, alt read good according to the charger. That's good.
Removed negative wire from battery, steel brushed the **** out of it and the mounting point + screw. It was quite dirty all around.
Checked all relays and fuses under the hood. The VSA Motor and Option relays weren't completely seated.
Idled for about 45min in my driveway while I detailed my headlights for corrosion and fogging.
Can keep you updated but after 3 drives today totaling about 30minutes, the issue hasn't surfaced yet.
What we think the original issue was
Bad battery ate alternator(only about 1 year old), and ate the new one by being shitty and spawned some gremlins.
Update:
Was good over the weekend and yesterday. Popped back on today on my way in to work. Going to check the relays at lunch.