Immobiliser woes

My 1994 Discovery has developed an intermitent fault with the immobiliser.
On a few occasions when the doors are opened with the key the immobiliser does not turn off hence I am unable to start the car. I have up to know been able to turn off the immobiliser by locking and unlocking the doors but this can take up to 5 mins and its getting worse.
Can anybody offer advice as to the problem ? Please keep it simple as my knowledge of auto electrics is very limited !!!
Is it possible to disconnect the immobiliser unit untill I can get it sorted.
Thanks

You may have an iffy micro switch, it's not unknown or the cam which operates both are positioned on the rear of the door lock, u need to remove the door card to locate it and check it's opration.

discool said:

You may have an iffy micro switch, it's not unknown or the cam which operates both are positioned on the rear of the door lock, u need to remove the door card to locate it and check it's opration.

Click to expand...

Thanks for that, would that be the front drivers door card ?

smilersmiff said:

Thanks for that, would that be the front drivers door card ?

Click to expand...

It would

I did find some pics of them on the web once IIRC there's two switches, one for the immobiliser the other central locking/alarm.

Quick update , the immobiliers has know decided to pack up all together !!! Are they expensive to replace ?

might be the spider, common fault I think.

All the immobilisor does is allow juice to the fuel cut off solenoid on the back of the injector pump (on a 300tdi anyway). Mine's now wired straight through to the in cab fusebox. Can't remember the exact fuse, but it's controlled by the ignition on the lower satallite box.