Alarm being behaving erratically

[lynnae endersby]

Hi there,

My 2002 E46 318i has been having issues with its alarm lately.

After the car has been locked and the alarm armed, the alarm goes off at random times. At first I thought something was triggering it, but this has started to happen more often, (and I could find no 'trigger'). Once I disarm the alarm and arm it again its usually behaves for a few days.

I then started noticing that the red light attached to the rear view mirror will randomly start flashing very fast. I can however still manage to arm the alarm. Inevitably the alarm will go off a few hours later, or I all four indicator lights start flashing. I have gone to check on the car a few times at night to find these lights flashing. I usually just open the doors and lock it again. This fixes the problem for a few days.

Does anyone have any idea what might be going on here?

I had a bad earth on one of my taillights a while back that have been fixed. The bad earth has returned again though (I just haven’t had the time to have it looked at again). Could this be related?

Thanks!
Lynnae

 

[zaleonardz]

Bonnet switch.... More then likely.

However, have the car go for a proper diagnostics, the alarm control unit records which sensor last triggered the event, and thats the one giving you your issue.

Experiance has however taught me that its the bonnet switch.

 

[Kobus328i]

I'm experiencing the exact same problem on my E30.

 

[Sankekur]

Agree with LZ on this, its probably the bonnet switch.


The fast flashing of the red light under the rearview (clown nose) that you see when you arm it is because it is reading one or more of the sensors for the alarm system as open but it arms the alarm system in anyway.

 

[outlaw335]

Agree with Lz! Its the bonnet switch.Im currently having the same issue,its highly annoying :argh: I have i-drive and a message constantly pops up saying that my bonnet is open.

 

[lynnae endersby]

thanks so much for all the help,

How will I go about fixing the bonnet switch though? Is it as easy as spraying the switch with some Q20 or is it more complicated than that?

 

[Sankekur]

I would just replace, if I am not mistaken it was something like R70 from the dealers. And to replace is really easy just disconnect the old one clip it out clip the new one in and connect it, doesn't take more than a minute.