Alarm Fault - My Car is a Metronome

[WigeonIncognito]

Hi all,

Today my 1997 R129 decided to turn into a metronome if I open the bonnet. It stops again with the bonnet closed, and starts/drives normally. The sound is coming from the alarm sounder, it sounds like it wants to go off but is just going bip bip bip bip at about 70bpm. Not a big issue at the moment, but I am cautious the fault may worsen or affect other things.

Does anybody have any advice about things to try or do? It has the single button remote fob with switch blade if that helps at all.

Thank you,

Matt.

 

[Petrol Pete]

Just un plug the alarm sounder , not sure if it's the same unit that plagues many an MB , but when it rot's out its internal batteries cause all sorts of Voodoo .

Unplugging it is a simple DIY cheap and cheerful fix ....if that's what it is of course.

One way to find out .

 

[WigeonIncognito]

Thank you @Petrol Pete for the advice. Re unplugging it, is it really as simple as just pulling the plug the leads from the siren on the wing? That doesn't seem an incredibly robust security feature!

 

[Wearsthefoxhat]

The sirens can corrode internally causing various faults within the unit. The car also has an alarm module in the boot, the fuse in the boot is labelled ATA.. might be worth pulling that to see if that is causing the problem..

 

[WigeonIncognito]

Thank you @Wearsthefoxhat that is useful information. I am about to do an 800 mile trip so it is good to be prepared with a couple of fixes to try.