MKIV 2003 V5 Alarm Problem driving me up the wall

[Billv5]

My V5 2003 has just developed a problem with the alarm. Having trawled the net I have no other issues. Windows, locks, interior lights all fine. This problem does not occur during the day only at night and around 10.00pm. The alarm will go off and continue until reset. Once reset it seems to settle. No idea why everything is fine. Tried locking with key but alarm activates again after a few minutes. Stumped any help welcome

[billayles]

Scan for fault codes.

Theres only a few things connected to the alarm which is the comfort module.

The boot / bonnet, the doors, and the ultrasonics.

If it's going off one of those will be causing it.

If it's the boot switch, the boot luggage light will be on, if it was any of the doors the puddle light on the offending door and the interior lights would be on.

If it is the bonnet switch thats easy to do just disconect the switch from the harness behind the drivers side headlamp and see if it's still going off.

It could be the ultrasonics so press the ''disable interior sensor'' switch under the drivers door jam, press once before you get out, arm as normal and that will disable the ultrasonics until you next disarm the alarm.

The fault code scan would help in this case and would probably tell you whats wrong.

It is a shame the standard alarms are not like cliffords or other makes where on disarm the alarm gives you a triggered input by flashing the led so many times to let you know what triggered the alarm.

Without this you guessing as to the cause.

I'd say it's either the bonnet switch or the ultrasonics.