Immobiliser on mk1 question.

I am after a bit of info to help me understand the immobiliser.

I recently purchased a really nice clean 1995 mk1 1.8 iS and all is well it runs well and drive nicely,  the specs for this car say that it was fitted with a immobaliser ( I would rather it didn’t have one ) the thing is it has what looks like a small led on the console near the switch that adjusts the mirrors but I have never seen it flash or light up either with the ignition on or off. The car does not have central door locking and the keys are just normal standard keys ( one Mazda one and one cut at the local shop ) there is no separate key fob. Just jump in the car use any of the keys and it starts…so how does the immobaliser work, what operates it ? . from memory there is a small white or metal coloured round button shaped thing About the 15 mm in diameter on the dash by my right knee sort of down by the bonnet catch,  Has this got anything to do with it.

any ideas how it is supposed to operate ( or maybe it has already been disconnected which would be good )


Thanks, Taz.

Sounds like it’s been disconnected, originally there would have been a touch key for the silver touch pad to the right of the steering wheel.

Thanks for the reply, I was rather hoping that this was the case, ,I take it that they have a habit of playing up and therefor get disconnected.

Yes they tended to play up, they were an after market fitting the cars towards the end of 95 had I believe a factory installed system that had a coded key.

The factory fitted immobiliser came in on UK cars at the end of 1995. This system uses keys with transponder chips that are about twice as thick at the top end as the keys on your car.

Be aware that the aftermarket immobiliser fitted to your car is probably still wired in but has been turned off. This means that there is a chance that it could still interfere with your ignition if there were a fault. If the car were mine I would remove the immobiliser completely and remake/replace the affected wiring.   

Cheers for the info, I will have a look and if it’s easy enough I will remove it.


They are usually wired in on the main ignition block wires and one other place.

From memory I had to remake 1 wire on the ignition block and another one or was it two in wiring on the drivers side near the sill. There were several other connections that required a joined wire to be removed and heat shrink / electrical tape used to insulate.

Follow all the wires and make a plan before you do anything.      


Cheers for the info everybody, old immobaliser disconnected and going to have a new thatcham approved one fitted.