Alarm Has A Mind Of Its Own!

[bigdavegrr]

Hey guys.

After working solid for the last year without a break, I finally booked a weekend off for my son to come down to Wales so we could spend some time together. We decided to hit the beach, and as soon as we got to the car park, with the engine still running, the alarm went off. After killing the ignition and starting again, it went off but resumed about 30 seconds later. We tried locking and unlocking the car - same result - it was if it was on a timer and went off every thirty seconds. By this time the car was attracting a lot of attention so we got in and drove it, with the alarm still sounding, 200 yards up the road. The only way we managed to shut it up was to disconnect the Battery then the siren itself which involved taking the undertray from the bumper and 3 hours messing in a hot sun.

Needless to say I wasn't very happy. This could have happened any other time than when my son was down and it wouldn't have bothered me. I now have to disconnect the Battery every time I leave the car for longer than a hour. It seems there's a backup Battery in the alarm system which makes a loud clicking noise every few seconds. After leaving the Battery disconnected for a while, the click stops, but starts when the Battery is reconnected. We tried to reset the system by holding the two buttons down on the key fob but this did nothing.

With the nearest Lexus dealer being 100 miles away in Cardiff, does anyone have a idea how I can at least get the car to function in a way where I don't constantly have to disconnect and reconnect the Battery? Or how to fix the system itself?

Thanks a lot

Dave