ok i have a 2007 mp3 250. Battery voltage is dropping fast whenever the engine is running, measuring <12v with the engine idling. Gotta keep a battery tender on it all the time.
The "hidden" fuse is good.
With the engine off, unplugged the alternator from the regulator. All 3 coils measure ~ .3 ohm.
Started it. All 3 coils, disconnected, measured 19.5 - 20.5 VAC while idling.
Shut off, disconnected regulator from battery. All 6 diodes were 530 - 540 mV forward voltage.
Reconnect alternator to regulator and start. Alternator measures 8.5, 9, and 9.2 VAC idling, and regulator outputs 1.65 VDC.
Reconnect regulator to battery. Kick tires and Cuss.
So are they both dead?