Alarm Issues (Not Bonnet Sensor?)

[andycoventry]

Hi all, first post so please be gentle.

I have a 55 plate E53 X5 3.0d and love it - best car I have ever had - Until Saturday night when the alarm was going off constantly (apparently - I didn't hear it but the neighbours did). I have read the many posts about the bonnet switch being faulty but it doesn't sound right in my case so I am appealing for help before I go home tonight to try and fix.

I got woken by a neighbour saying the alarm was going off, so I unlocked the car and re-locked again and within 5 minutes the alarm went off, unlocked it and re-locked it and the alarm went off again. Took it out for a spin and turned the car around in the space but again alarm went off within a few minutes of parking. I then moved the car to outside my flat where I could de-activate it from inside if it went off - but nothing. I then parked it outside my girlfriends house, nothing - outside the gym, nothing - on the road outside, nothing so I move it back into my allocated space thinking all was fine and the alarm goes off within 10 minutes.... this is driving me mad.

The only thing that has changed recently:

- The night it went off the first time the car had just done 700 miles pretty much non-stop back from holiday - so the battery should be fully charged.
- I had the coolant changed and brake fluid changed about a fortnight ago and have had the bonnet up a couple of times to top off and check the coolant.
- It was parked up a mountain in the very cold for a week last week but the alarm didnt go off then
- It has been very very wet here recently, and
- On the way to holiday the CD player packed in saying no discs I presume this is a seperate issue. 

My questions are these:

- If its the bonnet switch then surely it wouldnt be so location specific surely?,
- Is the system clever enough to determine a fault code or which sensor is causing the activation? if I take it for a diagnostic?
- Some have said it could be battery voltage low, but again it has had a long run and why so location specific?
- Can the system be set off accidentally by garage openers or other gadgets nearby? hence why it seems to only be at that one place,
- Any ideas gratefully received.

I need to do something tonight - I will try unplugging the sensor, taping it down and double clicking the fob later to see if these solve it - but any other ideas would help otherwise I think my neighbours will kill me.

[Johnny-p]

Getting the codes read will tell you exactly where the dodgy sensor is..

Had the same symptoms as you, it would sometimes go off minutes after locking sometimes I could leave it all night without any bother and mine turned out to be the bonnet sensor..

Unplugging it should tell you if it's at fault to save on diagnostic costs..

[storminmike]

[quote="andycoventry"]
Hi all, first post so please be gentle.

I have a 55 plate E53 X5 3.0d and love it - best car I have ever had - Until Saturday night when the alarm was going off constantly (apparently - I didn't hear it but the neighbours did). I have read the many posts about the bonnet switch being faulty but it doesn't sound right in my case so I am appealing for help before I go home tonight to try and fix.

I got woken by a neighbour saying the alarm was going off, so I unlocked the car and re-locked again and within 5 minutes the alarm went off, unlocked it and re-locked it and the alarm went off again. Took it out for a spin and turned the car around in the space but again alarm went off within a few minutes of parking. I then moved the car to outside my flat where I could de-activate it from inside if it went off - but nothing. I then parked it outside my girlfriends house, nothing - outside the gym, nothing - on the road outside, nothing so I move it back into my allocated space thinking all was fine and the alarm goes off within 10 minutes.... this is driving me mad.

The only thing that has changed recently:

- The night it went off the first time the car had just done 700 miles pretty much non-stop back from holiday - so the battery should be fully charged.
- I had the coolant changed and brake fluid changed about a fortnight ago and have had the bonnet up a couple of times to top off and check the coolant.
- It was parked up a mountain in the very cold for a week last week but the alarm didnt go off then
- It has been very very wet here recently, and
- On the way to holiday the CD player packed in saying no discs I presume this is a seperate issue. 

My questions are these:

- If its the bonnet switch then surely it wouldnt be so location specific surely?,
- Is the system clever enough to determine a fault code or which sensor is causing the activation? if I take it for a diagnostic?
- Some have said it could be battery voltage low, but again it has had a long run and why so location specific?
- Can the system be set off accidentally by garage openers or other gadgets nearby? hence why it seems to only be at that one place,
- Any ideas gratefully received.

I need to do something tonight - I will try unplugging the sensor, taping it down and double clicking the fob later to see if these solve it - but any other ideas would help otherwise I think my neighbours will kill me.
[/quote]

The bonnet sensor is the easiest thing to test...and i wish i'd known how to test before it sent me mad as per your post

I "overthought" the problem thinking BMW...super complex.....pull the cable from the switch and it will go into meltdown.....which it doesn't

Unplug the bloody thing and see what happens.....peace and quiet most likley. A neigbours X5 did the same 2 months ago, same problem,,,,,,same diagnosis....same fix

If its shuts up after unplugging leave like that and spend a tenner on a new one at your convenience at the dealer

Diagnosis of bonnet switch fail..............ZERO COST
Switch cost if needed Ten or Eleven quid ish.......LESS than diagnosis at dealer

[Stevejspm]

+1 on the bonnet switch, disconnected mine months ago with the intention of replacing the switch but never got round to it :-/
Disconnecting it shut the alarm up though