Ducato alarm system malfunction

Sounds frustrating! I had a similar problem with my old Renault Scenic, though it was a petrol engine. The alarm would just randomly go off, or sometimes not arm at all. Turned out, the issue was the car was trying to do too much at once. My mechanic explained it like this, imagine trying to juggle flaming torches while riding a unicycle – eventually, something's gotta drop! In my case, it was the central locking confusing the alarm. Have you had the battery checked recently? A weak battery can cause all sorts of weird electrical gremlins.

Interesting analogy. The battery seems okay, but I haven't specifically tested it under load. What exactly was the central locking doing to mess with the alarm?

Well, according to the mechanic, the alarm was coded to activate the optical locking (indicators flashing) on arming/disarming. It seems like the system was struggling to handle both the central locking and the optical confirmation at the same time, especially when the battery voltage dipped a bit. He suggested that could be the source of my grief. Honestly, electrical issues are like chasing shadows sometimes! I'd suggest taking it to a workshop with decent diagnostic tools; they should be able to pinpoint the exact problem.

Thanks for the insight. I took it to a local workshop, and it turned out the alarm system was indeed coded to activate the optical locking, as you suspected. They disabled that feature, and it seems to have resolved the issue. Total cost was 45€.