GOLF Alarm Problem (Interior Monitoring)

[djl78]

Hopefully someone has come across this prob before.
My father in law has a Golf GTI which has a problem with the interior monitoring part of the alarm.Basically when you press the button on the pillar next to the drivers seat the LED within the button should illuminate...in this case it isn't.
I've replaced the button....nil help??????
Any ideas would be greatly appreciated.

P.S. The back lighting within the button works as does the function itself i.e interior monitoring turned off,but there is no way of telling as the diode doesn't illuminate.

[popin]

According to the handbook. The interior monitoring system is switched on at the same time when the anti-theft alarm is activated. To de-activate it as you say you press the button and then lock the door. There is then a note that says that the light in the button will always be on when the vehicle is unlocked. It does not say anything about the light being on when the door is locked and the function dissarmed. It also says that the interior monitoring will automatically reactivate if the vehicle is locked after a door has been opened. So you have to press the button to de-activate the system every time before locking the door.

[djl78]

Totally agree but there is nothing to say that it has been de-activated once button is pressed prior to locking.
On my Allroad you press the button and the diode illuminates indicating system is disarmed.
I've checked part no's in Golf & Allroad and both are identical.
I need somebody to verify that diode illuminates if possible.
Thanks