BMW Forums : BimmerForums banner

1 - 10 of 10 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
hi all, my mum's z3 has an annoying problem, the alarm keeps going off ( normally early am). first thing I did was check the cctv to make sure no little **** was setting it off.
Bmw have fitted new battery, new tilt switch, and sensor in rear view mirror but it hasn't sorted the problem. any info or suggestions would be appreciated as it's drivin me mad. thanx, herby
 

·
Registered
Joined
·
30 Posts
One of the most common causes is the wiring into the boot lid, you need to peel back the outer cable & check it out.
Another common one is if the head unit has been changed as there is a sensor behind it what needs to be plugged
 

·
Registered
Joined
·
1,346 Posts
does the tell tale LED indicator not flash to indicate what sensor has triggered the alarm?

with the Z3 though - the 3 main culprits are those already discussed above

1. tilt sensor in boot -which often gets damp and can cause false alarms (it wouldn't matter if this had been replaced if they hadn't fixed the root cause of the problem i.e. if it was getting damp - which is usually down to the aerial grommet or the third brakelight gasket - but can also be down to the rear light seal to bodywork or the roof to bodywork seal)

2. contact sensor on bonnet (which is located on passenger side slam panel near headlight - there is a revised part for this which is slightly longer)

3. stereo sensor (if your mum has swapped out her head unit in the car then the replacement unit will not be making contact with the micro switch at the rear of the stereo - the stock BMW stereo has a bolt which depresses a micro switch when the headunit is in situ. It's a straightforward 5 min job to fix/bypass this with a cable tie though

HTH
 

·
Registered
Joined
·
21 Posts
2. contact sensor on bonnet (which is located on passenger side slam panel near headlight - there is a revised part for this which is slightly longer)
You can diagnose the bonnet sensor by disconnecting it. The alarm will set (although the bonnet is no longer protected) - if the alarm still triggers intermittently then you have a different problem, if it doesn't then the bonnet sensor is faulty.
 

·
Registered
Joined
·
51 Posts
Had a similar problem, and then the drivers door lock actuator failed about a month later. Fixing this, fixed the alarm also. - Just a thought...
 
1 - 10 of 10 Posts
Top