Hi everyone, I'm starting a new thread with a short summary of the whole issue (https://ducatimonsterforum.org/index.php?topic=80225.0).
My 2011 Monster 696 started having an intermittent starting problem some time ago. The first major issue was a battery that failed and leaked acid. Later the regulator was replaced as well, and since then I've gone through several battery and starting-system checks.
The main symptom was that pressing the starter button would sometimes produce a rapid "click-click-click" from the starter relay before the bike eventually cranked, or sometimes it would not crank at all. Once the starter motor actually turned, the engine would start almost immediately.
Charging voltage has been around 14 V and several batteries have been tested. The starter motor itself also seems healthy. The electrician found corrosion/moisture around the starter relay and replaced the relay, but the problem eventually came back.
One very important clue was that whenever the electrician bypassed the normal starter-control circuit and activated the starter directly, the bike cranked strongly and started immediately.
After checking the workshop manual, we confirmed that the starter button does not directly trigger the starter relay. The ECU receives the starter-button signal together with the neutral, clutch, sidestand and kill-switch inputs, and then decides whether to activate the starter relay.
The electrician has now bypassed the original ECU starter-control path and wired the starter command externally for testing. Since doing this, the bike has started perfectly every single time, including with a partially discharged battery. There is no more relay chatter and the ECU/dashboard is showing no errors.
He is leaving it untouched over the weekend and will test it again cold on Monday. If it continues working correctly, he will make a small, neat permanent auxiliary starter circuit.
At this point it seems very likely that the fault is somewhere in the original ECU-controlled starter circuit — possibly the ECU output/driver itself or something closely related to that path — rather than the battery or starter motor.
I'm currently leaning toward leaving the ECU alone if the auxiliary circuit proves reliable, rather than opening or replacing an otherwise perfectly functioning ECU.
Any thoughts or similar experiences with the M3C ECU starter output would be appreciated.
Will update in a month, I will be testing the bike during this period of time. However I decided to leave the auxiliary circuit for now.