my 97 e39 alarm sits quiet through the night and goes off in the daytime unmoved and untouched !can the temp effect it ?confused i am,is it possible to adj it at all,switch it off,where the heck is it ?as far as I`m aware its a std factory full closure alarm.

Door/boot opening,closure,deadlocks, interior lights and flashing led on mirror all work correctly !Couldnt be car battery as starts fine and has had a good run -could it ?  Help please. 

i do the valleting for a local honda dealer and when it is hot the cars in my unit lock themselves one after the other (even with the keys locked in the safer box!) the technitian at the dealer says its changes in atmospheric pressure

might be a similar thing here????

Alot of alarms that use ultrasonic sensors suffer this problem due as thaskitz says to change in air pressure/temperature. The reason is that it detects changes in the air flowing past the sensors and sees a change as an intrusion. Try parking the car in a shady area during the day to see if it still does it.

I can't say for the newer alarms but the older ones had a switch to allow you to disable the ultrasonics in case of hot days or leaving the windows open.

Russ