Urgent help regarding immobiliser mk3 gti 8v

[Adezmk3]

Hi,
Basically my car is parked miles away from me in my grans front garden being worked on, Annoyingly I've left the indicator on and left it like that so one headlight and rear light is on. Its been like it for about 8 hours so far (how long will it last.....?)
Anyway, as far as I know the car doesn't have an immobiliser, there is a toad alarm which I don't have a fob for and don't think is connected.
Is there an immobiliser in the ECU that could go awol if I let the battery go flat? Did all mk3 GTIs have this and do they get upset with a flat battery?
I can recharge the battery no problem but if it going flat will give me problems with an immobiliser I don't have a fob for I'd rather just drive there and switch the light off.
Thanks
Adrian

[Khare]

Early mk3's didn't have immobs but I think from 94 onwards they did. Won't cause any problems with immobilizer though.

[Adezmk3]

I should have said its a 1997 model, what does the immobiliser do then? I'm a bit confused about them (this is my first car that could have one, although I don't have a fob if it does)
So the battery going flat shouldn't upset it? What if I take the battery out to charge it?
Cheers
Adrian

[Deano2711]

The immobiliser is built into the ECU and works from the car key. As long as you use the car key then the immobiliser will be turned off.

[Adezmk3]

Awesome thanks, I suspect this car doesn't have an immobiliser then at all, the key is pretty basic, got a button on the side I think is for an LED light on the key which doesn't work.
Cheers

[Deano2711]

Pretty sure you will have a small chip type thing built into your key.

[Adezmk3]

oh ok, so getting another key cut isn't going to be as simple as buying a blank then either...
So all the immobiliser does then is stop the car being hot wired and driven off then?
Cheers
Adrian

[Khare]

1997 will have immobilizer. The chip is tiny, it fits inside the key (even if it looks basic).

To use another key you need to get the ECU coded to the chip in the key, wich will then render your original key useless.

And yes immobilizer stops car being hotwired.

[rubjonny]

unlikely flattening the battery would cause a problem with the immobiliser. ive got immob boxes that have been sat unpowered for weeks and they still kept the key matching. they dont even get power all the time, only when ignition is on.

and no, matching another key wont make the original useless

when you code a new key you need a matched key in the ignition so you can retrieve the SKC with vag-tacho, then you use the skc to match a 2nd key to the immobilser box. you dont touch the ecu for the key/immob matching process.

most good auto-locksmiths will be able to do this for you

[Khare]

Win! Gonna get a spare key cut then and coded, need to have a spare!