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[unlucky alf]

the last couple of days [including 10 mins ago] my alarm has gone off, its not the sounder side [if it has it] but the standard horn side, the interior sensors are turned off via the dash button so it shouldnt be them, after the horn has stopped waking up the neighbours the hazzards continue to flash, does the alarm have a knock sensor fitted or is it only on the doors, anyhow any ideas as this is upsetting the neighbours,,,,cheers

[markey mark]

bonnet sensor tim ! mine was same few weeks ago ! dissconectted it to make sure then replaced with a spare  

[Ian_D]

dont think they have knock sensors, but I'm just guessing at that.

Try unplugging the bonnet switch as they cause problems like this (its on the right hand side of the engine bay somewhere - next to the n/s top suspension mount.)

EDIT: To slow - thats what happens when you have msn messenger installed  

[unlucky alf]

cheers chaps, if i disconnect it can i assume that the rest is still going to work o,k or are they wired in series,,cheers

[Albatross]

Mine did this on and off for about a month about 6 months ago and then never since.

Weird. I reckon there must have been a mouse inside the car setting it off or something.

[unlucky alf]

well lets hope that shuts it up! it always seem to go off in the early hours when im all tucked up in bed as is the "law of sod"] is there any point in replacing this switch as the doors have to be opened anyway to open the bonnet

[Andy B]

well lets hope that shuts it up! it always seem to go off in the early hours when im all tucked up in bed as is the "law of sod"] is there any point in replacing this switch as the doors have to be opened anyway to open the bonnet

As said, it's not usually the switch itself but the bracket it's fixed to. It's a normally closed switch, that's opened as the bonnet closes but then closes when the bonnet's opened or flexes due to heat  :-? If the switch is not there it can't close, so the alarm is happy. Providing the switch is OK it'll just be the bracket.

[feeutfo]

As Andy says, on my pre face lift, i just bent the bracket up to meat the bonnet so it gave more contact when closed, thus pushing the switch further down. I always put it down to the weather/heat/ rain making the bonnet expand and contract?
That just being enough to set it off with bracket being a bit low.

 On my face lift they moved the bonnet switch to the drivers side wheel arch, a much more solid mounting point, which confirmed my theory, imho.
So yeah, basically, just bend it up a bit.

[Andy B]

......
 On my face lift they moved the bonnet switch to the drivers side wheel arch, a much more solid mounting point, which confirmed my theory, imho.
So yeah, basically, just bend it up a bit.

But, as MarksDTM pointed out to me, you also have an bonnet switch loom plug over on the passenger side too.  :-?      

[unlucky alf]

thanks chaps ive disconnected it for now & will leave it for a few days to make sure it is the switch, will test the switch in the meantime with a meter to see at what point it closes, but going on what others have said i`ll probably give it a tweak even though i still cant see the point in it in the first place

[davlad22]

dont think they have knock sensors, but I'm just guessing at that.

I would be inclined to think otherwise, we've had astras and even on the omega when it rains or hails REALLY hard it sets the alarms off.  

[Dave DND]

dont think they have knock sensors, but I'm just guessing at that.

I would be inclined to think otherwise, we've had astras and even on the omega when it rains or hails REALLY hard it sets the alarms off.  

Some of the early interior sensors were also Frequency sensitive to allow for broken glass, and these were often set up by the dealers by rattling a set of keys inside the car to get the correct sensitivy for them.

Problem was that hard rain and hail on the glass can often hit the same frequencies as the glass actually breaking !! - turn the sensitivity down a little and all should be well.

 

[unlucky alf]

right the update is; i disconnected the bonnet switch & while i was at it turned off the interior sensors via the dash button, today the bleedin` alarm went off again!, so i suppose the next thing is to remove the door switches & check them, cant recall seeing a switch for the tailgate though, has this got a mercury switch? if there is anything else to check please let me know as im on an RAF base all weekend & they take a dim view of alarms going off!!

[unlucky alf]

cleaned up all the door switches today, went to the shops & parked up, 3 mins later my alarm was going off again!, so now its going to be wire checking time where abouts is the alarm unit as im figuring thats the place to start first.

[Dave DND]

Long shot - but how about a faulty / discharged back up battery in the siren giving a voltage drop problem?

Clutching at straws I know ?

[elite3.0v6tourer]

I HAVE THE SAME ISSUE....
I have disconnected the bonnet senor, the horn and black box thingy under the scuttel board,had a new battery fitted yesterday and the bloody hazzards were still flashing last night,doing my head in,i cant find the main control unit for the alarm just to turn it off or even a fuse to disarm it,any help please as not able to use as unable to lock even with the key as this sets the alarm too!!!!!!!

[unlucky alf]

right, ive just got back from my weekend in sunny brize norton!, i dont think the alarm went off as nobody mentioned it, but ive just got home & parked it up & after an hour its decided to let the neighbours know im back , thanks for the idea of the sounder unit Dave & i`ll see if its connected or not & if so disconnect it, out of interest sake how long do the hazzards flash after the horns shut up?

[unlucky alf]

just one other thing, have all miggy`s got the separate sounders?, only as mine is an older one, so maybe they were only on the later models. :-/

[markfree]

Posted by: elite3.0v6tourer Posted on: 14. Nov 2008 at 07:38
I HAVE THE SAME ISSUE....
 

So do I and it's driving me nuts as well but fortunately I can put the car in a locked garage without locking the car (and have a peaceful night sleep).
What happens with mine is the alarm is set off anything up to 20 mins after parking - horns, lights & powersounder all go off - disconnected the bonnet switch but made no difference - what I have noticed is that when I lock the doors and set the alarm the red led on the centre console flashes constantly for 10 secs and according to my handbook there is a system fault.
What I'd like to know - Is the alarm connected to the ecu and can you read the error codes to determine what the problem is?

[elite3.0v6tourer]

I've got to the point now where i want to find out how to compleatly disarm the fu*ker,but no one seams to want to tell me where all the wires go too ie wires from the indicators,so i can just get rid off,not bothered if it keeps going off as long as i, A.cant hear it and B.cant see it. LOL

[Kevin Wood]

Sounds like a faulty power sounder to me. Even if it's not sounding itself, it can send a signal which sets off the main alarm.

Mine did this on and off for about a month about 6 months ago and then never since.

Sounds like the power sounder too. The backup batteries leak, it panics and sets off the main alarm for a while and then the leak gets so bad that it takes out  the signalling line to the main alarm and all is quiet. I would pull it out, though, because there have been one or two instances of fires starting in that area, and the power sounder is only protected by an 80 amp fusible link (and it's fed through a poxy wire).

Kevin

[Kevin Wood]

By the way, a Tech 2 can be used to determine exactly why an alarm has been going off.

Kevin

[markfree]

I took the alarm/power sounder out of the car and it's now all quite on the western front - there's a recent post in general help in which the guy says that his went on fire - glad I took mine out now
By the way you can lock your car without setting the alarm by closing all doors then open rear o/s door and reach in and close all doors via o/s front door button then close rear o/s door - works on mine anyway - I know this because the red led on centre console doesn't flash - dont leave keys in ignition

[unlucky alf]

mine just keeps getting stranger!, ive gone out this morning to find the sounder with a view to uplugging it, ive lifted up the scuttle plastic & all ive found is a standard car horn!!!, this might explain why ive only got a single tone on the hooter as there is only 1 horn in the front , unless of course mine being an older one it doesnt have the piezzo sounder with battery backup, any ideas?

[Kevin Wood]

The horn under the scuttle is only used as an alarm sounder. The main horn(s) are under the passenger side inner wing IIRC.

Kevin

[unlucky alf]

cheers kevin,sorry i assumed that the power sounder was built into the battery backup box, anyhow still no box or any 4 pin plug that would suggest one being there in the first place