2015 Monster 821 Starting Problem

willno said:

Thanks for your reply Baggerman. I thought it was the relay but it's not because I bench tested it and it was OK. Since all three of the relays are the same I swiched them out and still had the problem. I also went through the connector and fuse checks you suggested. I didn't find anything but just pulling the fuses and checking wires and contacts may have helped. I took the kill switch and starter button apart and checked the 12V at the button. I cleaned the contacts with contact cleaner and put it back together. When I tried it this time I noticed the starter sounded like it was trying to turn over. I charged the battery, tried it again and it cranked. I think the problem is what I call VooDoo electrics. That's when the bike sets up for a while without being used, the contacts oxidize a little, the battery voltage drops a bit and things work sometime and sometime they don't. It creates a nightmare when you're trying to track down an electrical problem. You test something and it doesn't work so you think your on the right track then 10 miniutes later you test it again and it works. I'm sure you have run into that.
Anyway, I have always noticed that the starter always seems to be weak, no matter what the battery voltage. Do you know anything about that. Thanks again.

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baggerman said:

Ducati is kinda of notorious for using too small a wire gauge on the cable from the solenoid to the starter. Use a DVM and check resistance from the starter hot lug to the battery negative side. Then check resistance from the other end of the starter cable to ground. Should be just a few ohms and the reading should be pretty much identical from both measurements. If the second reading is significantly higher go to a larger gauge cable. That should help. I raced a high compression 2 valve years ago and it couldn't be started with the stock cable on the bike.

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• Ensure your battery is fully charged and holding at least 12.6V when at rest.
• Under load (while cranking), it should stay above 10.5V. If it drops below that, your battery may be weak.
• Check battery terminals for corrosion and ensure they are tightly connected.

• Since the wire to the starter relay comes from the ECU, test if the relay is receiving a start signal.
• Use a multimeter to check for 12V at the relay coil terminals when you press the starter button.
• If you don't get 12V at the relay, the ECU might not be sending the signal due to another issue.

• Check if the starter button is actually making a connection. A worn-out switch can prevent power from reaching the relay.
• Inspect the clutch switch and kickstand switch. If one of these is faulty or disconnected, the ECU may not allow the engine to crank.
• Try bypassing the clutch switch temporarily to see if it makes a difference.

• Make sure the ECU has good ground connections and proper voltage supply.
• A corroded ground or weak ECU power connection can cause strange behavior.

• If the bike has a check engine light, try plugging in a diagnostic tool to check for error codes.
• Some Ducati models require a Ducati-specific OBD2 adapter to read ECU faults.

• If your immobilizer is not recognizing the key properly, it may prevent starting.
• Try using a spare key if you have one.
• Look for an immobilizer warning light when you turn the ignition on.

• Inspect all fuses, especially the starter relay fuse and any ECU-related fuses.

• If everything else checks out and you’re sure the ECU isn’t sending the signal, it may have a fault.
• Before replacing it, see if a Ducati dealer or a technician can test it.