Hi everyone, I’ve had my 2003 1.8 Sport from new and was of the understanding that it didn’t come with a factory fitted alarm but an immobiliser instead, but now think they may be one and the same thing?
Anyhow my neighbour has advised that the car has been beeping and flashing its lights on more than one occasion whilst I’ve been out (I’ve not had any modifications installed).
From reading various threads I am speculating that this may be due to a microswitch failing. I think there is one of each in the boot, driver’s door, and passenger door (and maybe also one in the bonnet making four in total).
To keep on the right side of the neighbours (who I kept awake last night!) I’ve disconnected the battery. ![]()
Is anyone able to spell out for me the correct sequencing of setting/unsetting the alarm using the manual key with doors and boot to try and identify which, if any, is failing please?
Ps I’ve never changed the battery in the key fob as it still appears to work fine - could this be a potential cause?
Many thanks in advance!
Marco
I am not able to fully answer your question but can talk a little about what I know to save your wasting time in certain areas.
The factory immobiliser is totally separate to the alarm. It is however coded to the transponder chip in your keys and the ecu under the passenger carpet.
Also under the passenger carpet next to the ecu is the alarm module, a black plastic box, marked NC87 67 790.
There are cables with microswitches - red on drivers door, yellow on passenger door and black on boot. If your fob is unlocking/locking both doors and the boot with the central locking function, I would say these are all fine.
I would think that there is also a contact switch under the bonnet. This may be where the problem lies.
Thank you Rhino for your reply.
I’m not yet familiar with the location of the bonnet switch however my instinct is with the boot switch. Reason being, unless a complete coincidence, I have been investigating a boot leak and have removed all of the boot trim, including the covering of the boot latch where there are wire/electronics.
I’ve identified that the leak is coming through the rubber boot lid seal (getting in there through the bodywork seams above the number plate area) and then running out and dropping into the boot either side of the latch. As a result of the leak there is a lot of condensation underside of the boot lid that may be dripping down onto the wiring/microswitch now that it is exposed.
I will start with that and hope the issue is the water ingress.
Quite likely Marco
a common cause of microswitch failure is water ingress.
Perhaps the water is causing the switch to misread.
Lots of rain recently to compound the problem.
Perhaps I imagined the contact switch under the bonnet? - no MK2.5 car around to check.
Mmm… I’m still scratching my head!
Here is the current position: -
Inspected the micro switch in the boot - removed from key barrel, very clean and dry as a bone, wires look ok, no broken plastic, refitted to key barrel.
I then re-connected the battery - unlocking and relocking the drivers side door using the manual key causes the amber lights to flash, and unlocks/locks both the driver and passenger doors - so I think both of the door micro switches are fine?
Put a new battery in remote key. Using remote key achieves same results as above. And also works with the boot lock.
The only thing I’ve noticed that might not be quite right is… on pressing remote key boot button, occasionally does not activate boot lock.
Anything else to test/check?
Now sitting indoors wondering if the alarm is going to go off! ![]()
Sorry, forgot to mention that the red light on the dash no longer flashes. I don’t know if this is a new thing or not, or what this means?