518i SE Alarm Buzz

[teedee9]

Hi folks, hope someone can help me? I have a 1996 518i with a factory fitted alarm.
I don't use the car a lot as I am a white van man and work away during the week. My car has always been fine when left all week but a few weeks ago the battery was flat when I came to use the car. I jump started it and all was ok. This weekend it happened again, so I took the battery off, fully charged it and then had it checked to ensure it was good. The battery is fine and the charging is fine so I assume something is draining the battery.
The main problem is that now when I connect the battery the alarm siren is making a funny buzzing noise. Also the alarm set chirp does not sound. I assume that the alarm has its own batteries and that these are drained. I cannot stop the alarm from buzzing when I press the alarm fob. The indicators still flash and the car starts ok, and everything is working ok.
Any ideas as to what is going on?

[witeshark]

As a guess, the alarm may have a bad relay.

[teedee9]

Sounds feasible to me. I assume the alarm system is located under the back seat, is it just a matter of trying each relay until it stops?

[marti5]

could require new Batt in fob? How old is the car batt ?

[teedee9]

Battery in the fob is fine. Car battery has been tested and is in excellent condition. As I said originally everything works OK except the damn siren is buzzing and I can't stop it.
Does anyone know where the backup battery is for the alarm? and how do I recharge or replace it?

[teedee9]

The buzzing problem has now buzzed off! Re-connected the battery after it had been disconnected all week and voala everything is fine, alarm works, central locking and alarm chirp is back. This must be the best car in the world, it mends itself? or was it because it was Halloween? Thanks anyway.

[witeshark]

Glad to hear it!

[marti5]

Bmw's have strange things happen, if I ever get a problem the 1st thing I do is disconnect the batt for 15 minutes.