997 - paranoid alarm

[Adam B]

In last couple of weeks have found my alarm going off for no particular reason, was fine before, not sure how often as not around to hear it apart form evening and weekends but it is very intermittent. Worrying given how crap how Porsche's seem to drain batteries.

Before taking it to my specialist are there any simple checks I can make?

thanks

[drmark]

Start with your battery

[Adam B]

Battery was replaced with a decent Bosch (not the crap OEM one) last year.

not following - do you mean battery low charge or defect is causing alarm to go off?

[gilliambot]

It may sound strange but make sure your glove box is properly shut, apparently this can disturb the alarm if its not. I had the same problem and a PHer suggested it to me. It solved the problem.

[anonymous-user]

I think he is referring to the battery in the alarm siren itself, the alarm has its own battery so if the main battery is disconnected it doesn't stop the alarm working.

[Demort]

Simple check ... clear out any coins you have in the ash tray or center consol ... the interior monitor is under there and coins interfer with it.

I think the battery comment may have meant is the battery going flat , a drain on a battery will also cause an alarm to go off .

The fault is probably the alarm seeing a switch signal from doors/boot .. etc .. and you need a tester to see the actual values for this.

With a tester you can also see the events/actuation list so it will tell you what triggered the alarm.

[996TT02]

I'm assuming it has a vibration/shock sensor it's quite possibly too sensitive. Sometimes my (non Porsche) alarm goes off when a loud car drives past and causes mine to resonate even though actually shaking mine won't set it off.

Re the (car) battery I doubt it, sometimes mine has gone flat and certainly the alarm is not set off, yes voltage drop does set it off but it must be rapid such as when disconnecting the battery with the key out of the ignition.

Same with the alarm unit battery, mine sometimes lives with the car battery disconnected for an extended period, the alarm battery eventually drains but the alarm does not go off. I know it drains because after reconnecting the (car) battery, if I crank the engine immediately or almost then the alarm DOES go off, again due to rapid v-drop at the unit. If I don't start it up for an hour or so, or put the battery on charge while connected, then the alarm battery gains some or a full charge, and there is no sounding of the alarm upon start up as the unit's battery makes up for start up v-drop.

So no, I don't think a depleted battery whether the car's or the unit's will cause the alarm to go off.

[anonymous-user]

Well if Porsche alarms are the same as Audi then a dying battery in the siren will cause random alarm triggers, this is a well known issue with Audi vehicles.

[Adam B]

Thanks all, was going off tonight again - I was out for a drink but OH heard it a few times

Have removed coins from ashtray, and ensured glovebox is properly closed

Looks like I need to get closure points tested and alarm battery looked at

[drmark]

Adam B said:

Battery was replaced with a decent Bosch (not the crap OEM one) last year.

not following - do you mean battery low charge or defect is causing alarm to go off?

Sorry missed this. Common problem with failing Moll battery but recent Bosch unlikely to be cause so ignore me