E9x M3 Charging Issue After Alternator Replacement — Tachometer Jitter
E9x M3 Charging Issue After Alternator Replacement — Tachometer Jitter
I’m having a strange charging issue with my E93 M3 (S65) and wanted to see if anyone has experienced something similar.
The car originally threw a “Charging Malfunction” warning. At the same time, I noticed the tachometer needle started becoming jittery/unstable. I believe the tachometer issue is directly related to the charging/voltage problem.
I replaced the original alternator with a Bosch remanufactured alternator. After installing the replacement, the original charging malfunction warning/code went away, but the car is still not charging the battery.
The tachometer is still jittery, which makes me think the underlying charging/electrical issue hasn’t been resolved.
A few things I’ve noticed both before and after replacing the alternator:
Original alternator caused a charging malfunction.
Tachometer became jittery when the charging issue started.
Replaced the alternator with a Bosch remanufactured alternator.
Charging malfunction warning/code is now gone after the replacement.
Battery voltage is only around 11.5–12 volts, both with the car off and while the car is running.
The battery is not being recharged while the engine is running.
The tachometer remains jittery before and after the alternator replacement.
I checked the connections at the alternator, including the B+ terminal.
I’m also looking into the alternator fuse/fusible link and wiring.
At this point I’m considering replacing the Bosch remanufactured alternator again, but before doing that I’d like to make sure I’m not overlooking something such as:
Alternator fuse/fusible link
B+ cable or connection
Ground connection
BSD/IBS communication
Alternator voltage regulator
Wiring between the alternator and DME
A defective replacement alternator
Has anyone with an E9x M3/S65 experienced a similar situation where the charging malfunction and tachometer jitter occurred together, and the car continued not to charge even after replacing the alternator?
Any suggestions for what I should test next would be greatly appreciated.