Alarm Problem after battery change

[Richard Hamilton]

1998 Tiptronic Coupe RoW (UK).

The battery only just started the car last night, so I fitted a new one this morning - Bosch Silver 75Ah. I used the normal procedure of switching the ignition on before disconnecting the battery. When I reconnected it there was a single chirp from the alarm siren about 10 seconds after I connected the negative terminal.

Now, every time I remove the key from the ignition I get a single chirp from the alarm siren after a 10 second delay. Then, when I lock the car I get a double-chirp from the siren, but the LED single-flashes every 2 second or so (as it should). There are NO faults shown a PST2 test.

I have to say this is the first time I have ever heard the alarm siren. On the occasions that I have left the oddments cover open and locked the car, I got a single-beep from the car horn - not this loud chirp from the siren. I have disconnected the battery for about 10 minutes and reconnected it. Still the same, and no faults in the memory.

I KNOW this is going to drive me crazy, so before I disconnect the alarm siren by unplugging it, has anyone else experienced this problem? My initial thought is that something in the alarm control module has been corrupted during the battery change.

edit: It just occured to me - Could it be the backup battery in the siren?

Edited December 5, 2006 by Richard Hamilton

[claudiu]

What a coincidence! I have also replaced the battery this weekend, having gone flat, but there is no chirping. However, I didn't know about the trick with the key in ignition, hence I have been almost totally deafened by the siren till I got help over the phone from the Porsche garage...

[Richard Hamilton]

Well, I think I've worked out what was wrong, for those who are interested.

When the battery was disconnected the alarm controle module went back to the default settings. On UK cars we have an alarm siren and tilt sensor, and the default settings for these devices is "active". I have deactivated these, so now I am back to normal operation. The only snag is that there must be something wrong with either the tilt sensor or siren. Oh, well. Do I worry about it? I was blissfully ignorant about it before................

[claudiu]

Well, I think I've worked out what was wrong, for those who are interested.

When the battery was disconnected the alarm controle module went back to the default settings. On UK cars we have an alarm siren and tilt sensor, and the default settings for these devices is "active". I have deactivated these, so now I am back to normal operation. The only snag is that there must be something wrong with either the tilt sensor or siren. Oh, well. Do I worry about it? I was blissfully ignorant about it before................

Ignorance is blissful sometimes...

[hunteje]

I saw your note about turning the ignition on before removing the battery to avoid alarm problems. I have never heard of this. Can anyone tell me about this. Thanks

[Richard Hamilton]

It stops the alarm siren from going off, as there is a backup battery in the siren. If the battery is disconnected without the ignition being on, the alarm thinks someone is trying to steal it!! That's the way it works on UK cars anyway.