Having put the bike (2016 Piaggio MP3 500 with 40k miles), successfully, through its MOT today, the engine management light decided to make an appearance on the way home from the testing centre (Sod's Law…).
Initially, the ASR light came on and a little later, the engine management light followed. I did have a sneaking suspicion that the management light was something to do with the battery voltage being low as I know, courtesy of the fine members of this forum, that the ASR light is temperamental where low battery voltage is concerned.
I arrived home in one piece and started to have a poke around. The battery voltage was approx 11.5v so I replaced that battery with the spare I have that I keep on a maintenance/tender charger. I'm confident that we can rule out the battery being the issue as my batteries are not old and I do keep them topped up.
Upon starting the bike with the fully charged battery, it became clear that there was an issue with the charging system as the voltage never increased when the bike was at idle (I used my multimeter to detect this), revved or rode up and down the street (I used the voltage display on the dashboard to see what was happening when I was riding and revving..).
I checked the fuses under the seat and they were okay for continuity (including the 30A fuse associated with the starter relay).
I followed the MO for checking the stator on the Partzilla website….
Stator Ground Test (Pin to Pin..)
0.3ohms, 1.1ohms and 1.0ohms
Stator Resistance Test
Open line on all three pins when individually associated with a ground point.
AC Running Test To Ground At Idle
4.2v, 5.5v and 6.6v
AC Running Test Pin to Pin At Idle
12v, 10.4v and 7.4v
I apologise for not providing any AC Running Test values while the bike is being revved. I was on my own and I just couldn't manage to acquire a value and rev the bike at the same time….
If anybody can help me resolve this situation, I would be most grateful and I'm happy to provide any more information that might be useful. To my mind, it looks like the stator or VR might have failed….
I had promised my Gran that I would visit her tomorrow but with the bike in this state it won't be possible. The sooner it's working, the sooner there'll be an old lady who is a good deal happier… Thank you in advance for your help