Alarm going off - 2006 E86

[Fred Smith]

Everyone else unplugs the sensor and tucks the wire back out of the way. Never heard of that not working before. I’ve done several myself and bought cars that have had it done. Pull the plug off and carry on using the key fob to lock unlock and activate the alarm.
Seems you have a unique problem?

Your Z4 knowledge is clearly very good! [I knew that already!]

I've just tried again this morning and with the bonnet sensor connected the alarm went off within about 5 or 10 mins.

But unplugging the sensor today has NOT stopped the remote working, and I've locked the car with the remote and 30 mins in the alarm has not gone off. I swear that yesterday the remote stopped working when the sensor was disconnected. Who knows, but yesterday was probably user error (me pressing "unlock" and wondering why the car won't lock?)

What's the best way of checking that the alarm is actually set? Or is it pretty much impossible that remote locking could have worked without setting the alarm?

 

[enuff_zed]

What's the best way of checking that the alarm is actually set? Or is it pretty much impossible that remote locking could have worked without setting the alarm?

Set the aLarm by locking with the remote.
Wait long enough for it to arm.
Then unlock the door by using the key in the lock and open it. That should set the alarm off.
Then wind the windows down, lock with the remote, wait as before, then stick your arm inside and wave it about. That should test the motion sensor.

 

[Fred Smith]

Set the alarm by locking with the remote.
Wait long enough for it to arm.
Then unlock the door by using the key in the lock and open it. That should set the alarm off.
Then wind the windows down, lock with the remote, wait as before, then stick your arm inside and wave it about. That should test the motion sensor.

Thanks again.

The remote is setting the alarm even though the sensor is disconnected, and the alarm is working both ways you suggest it should. The alarm does not seem to be going off.

Why does the bonnet sensor trigger the alarm?

 

[enuff_zed]

Set the alarm by locking with the remote.
Wait long enough for it to arm.
Then unlock the door by using the key in the lock and open it. That should set the alarm off.
Then wind the windows down, lock with the remote, wait as before, then stick your arm inside and wave it about. That should test the motion sensor.

Thanks again.

The remote is setting the alarm even though the sensor is disconnected, and the alarm is working both ways you suggest it should. The alarm does not seem to be going off.

Why does the bonnet sensor trigger the alarm?

I would imagine that because it points upwards it gets moisture seeping into it. A lot of people even go as far as completely removing the sensor and its mounting bracket, but you could probably find a replacement sensor if you wanted to.

 

[Fred Smith]

I would imagine that because it points upwards it gets moisture seeping into it. A lot of people even go as far as completely removing the sensor and its mounting bracket, but you could probably find a replacement sensor if you wanted to.

I actually meant "why is the bonnet sensor connected to the alarm at all, what the hell have the two things got to do with each other?" My question assumes that people can remember to shut the bonnet before locking or leaving their car.

Whether I was trying to ask it or not, I do appreciate your answer!

I'm not sure I see the need to remove the sensor and bracket - like broken headlight washers / pipework etc I believe best practice is to leave it all in place in case the next owner wishes to make the car as OEM and fully working as possible. I will add replacement sensor to my very long list of jobs, quite near the bottom, maybe to never be reached!

 

[enuff_zed]

I would imagine that because it points upwards it gets moisture seeping into it. A lot of people even go as far as completely removing the sensor and its mounting bracket, but you could probably find a replacement sensor if you wanted to.

I actually meant "why is the bonnet sensor connected to the alarm at all, what the hell have the two things got to do with each other?" My question assumes that people can remember to shut the bonnet before locking or leaving their car.

Whether I was trying to ask it or not, I do appreciate your answer!

I'm not sure I see the need to remove the sensor and bracket - like broken headlight washers / pipework etc I believe best practice is to leave it all in place in case the next owner wishes to make the car as OEM and fully working as possible. I will add replacement sensor to my very long list of jobs, quite near the bottom, maybe to never be reached!

Fair enough, yes it won't hurt to leave it where it is.
I suppose someone may try to open the bonnet to steal something from under it? Who knows?