I have a 1999 vauxhall vectra sri.
The other day the remote stopped working on the key even tho the light still comes on.
So i've had to lock the car with the key which is fine,
But when reopening the car door the alarm goes off. The only way to switch it off is to turn the key in the ignision and start the car.
I have been told if i disconnect the alarm i will probably have problems with the Immobiliser.
Can anyone help please ?

Dave J, November 2009

Try re-synchronising the key.
Key in ignition, turn ignition on ( dash lights on, dont start engine).
Press lock button on key fob. Doors should lock then unlock. You may have to push the button a few times.

If it loses sync again you may need a new fob battery.
The fob battery connections can sometimes break causing loss of sync, check the soldered joints.

Do you have a spare key, if so does that work?

vaux, November 2009