I'm at my wit's end on this issue. I've been chasing it for awhile and posting on M6G, but thought I'd see if this is something more common in tracked vehicles via heat-fried or vibration-affected components. Recap:
Behavior: "Charging System Service Now" light pops on within about 5 seconds of startup, stays on steady for the remainder of the time the vehicle is running. On one drive (unclear what made this drive different), the center stack, HVAC, and other power shut down, and AdvancTrac disabled.
Checks and attempted fixes:
Any ideas? Specific connectors grounds to check? Specific Forscan checks? Specific voltmeter checks? Otherwise, I will indeed throw another part at it and put the harness in. If I have to go to a dealer, I can try that, but my confidence is low in that path. They refuse to diagnose without all OEM parts (so I'll have to reinstall the alternator and the possibly-failing OEM battery), and last time this happened they failed completely to figure out the issue (though different dealer). If they just go fishing, the labor and parts are on my dime with no guarantee of a fix. My suspicion is they will likely want to replace everything I've already tried with new OEM parts and labor, which is a waste of time and money.
This issue is driving me nuts, and I have a race this weekend.
Behavior: "Charging System Service Now" light pops on within about 5 seconds of startup, stays on steady for the remainder of the time the vehicle is running. On one drive (unclear what made this drive different), the center stack, HVAC, and other power shut down, and AdvancTrac disabled.
Checks and attempted fixes:
- Voltage meter on dash typically jumps up to ~15.2V after startup, settles into mid-14V range steady. On the one drive, voltage meter went completely crazy.
- No voltage drops anywhere in the fuse box.
- Forscan shows slight difference between battery voltage requested and system voltage (14.56V vs ~14.8V - 14.9V respectively). This is after pigtail and battery replacement, before alternator replacement.
- Visual and manual inspection of wiring harnesses, grounds, and connections that I can find shows no obvious issues. Connections are tight, non-corroded.
- Replaced the alternator voltage regulator pigtail. No change in behavior. This was the cause of my problem last year (much more sporadic on/off/on error message) and I replaced it then, fixing the issue.
- OEM battery read low after sitting. Replaced the battery with a fully charged AG ATX20-HD, performed the BMS reset several times (both non-Forscan and Forscan versions). No change in behavior. (To be clear, the one time the system went crazy was after battery replacement).
- Replaced alternator. No change in behavior, though I haven't driven the car around since this, just driveway start and idle testing.
Any ideas? Specific connectors grounds to check? Specific Forscan checks? Specific voltmeter checks? Otherwise, I will indeed throw another part at it and put the harness in. If I have to go to a dealer, I can try that, but my confidence is low in that path. They refuse to diagnose without all OEM parts (so I'll have to reinstall the alternator and the possibly-failing OEM battery), and last time this happened they failed completely to figure out the issue (though different dealer). If they just go fishing, the labor and parts are on my dime with no guarantee of a fix. My suspicion is they will likely want to replace everything I've already tried with new OEM parts and labor, which is a waste of time and money.
This issue is driving me nuts, and I have a race this weekend.