I've checked all the switches: doors, boot, glovebox, bonnet. All of them seem to be of the type that breaks contact when the 'door' is closed, so it's hard to see how they would accidentally re-contact whilst closed. They all seem to be functioning correctly and more than switch.
Based on further understanding gleaned from searching the forums here for a couple of hours, I have determined:
- I can workaround the problem with the trick to lock without arming the alarm: with driver's door shut, open passenger door, lean in to hit the 'lock' switch on the console, then close passenger door.
- When I arm by locking the door with the key, the flashing LED in the door pins flashes twice repeatedly. I understand this means that some part of the alarm isn't armed properly, which might be indicative.
- At some times in the past I've had funny issues where locking with the remote would immediately unlock again. I think this suggests I need to take the doors apart and have a good clean/adjust/lube of the door handle mechanisms.
- I'm also wondering if the new radio I installed a few months ago is implicated. I understand the alarm is connected to it in one or two ways, but I don't understand how exactly. Can anyone help me understand that?