car won't start-help with alarm/immobiliser issues

[mackenzie50]

And the alarm siren is going?

Oh Yes!!

[mackenzie50]

'The factory immobilser doesn't stop the engine from turning on the starter motor, just stops the engine so if you can't turn the engine over you either have an aftermarket alarm/immobiliser or some other problem like a faulty ignition switch.'

Thanks very much for your input, John- and I think it was Andy who originally wondered if there might be an ignition switch issue too....

[K Simmonds]

Yep, a faulty ignition switch could be the cause of your problems, their not all that hard to change so it isn't a big problem. To speed up diagnosis you can use a spare ignition barrel/switch assembly with key, simply disconnect it from the one on the car, hook it up to the spare and give it whirl. If it goes you've found the culprit.

We need to know if you have any other (non factory) alarms or immobilisers on your car mate. The rectangular pods you mention sound like ultrasonic sensors, which I didn't think Audi alarms of the era had, my 1995 RS2 certainly doesn't have them but does have a factory alarm.

[mackenzie50]

Yep, a faulty ignition switch could be the cause of your problems, their not all that hard to change so it isn't a big problem. To speed up diagnosis you can use a spare ignition barrel/switch assembly with key, simply disconnect it from the one on the car, hook it up to the spare and give it whirl. If it goes you've found the culprit.

We need to know if you have any other (non factory) alarms or immobilisers on your car mate. The rectangular pods you mention sound like ultrasonic sensors, which I didn't think Audi alarms of the era had, my 1995 RS2 certainly doesn't have them but does have a factory alarm.

Cheers Kit, and thanks to all so far who've contributed, very grateful...but without the further neccessary info from my end ,eg. photos- can't expect further diagnostic success from you guys...watch this space!

[K Simmonds]

No worries Col, we'll have your car running again soon I'm sure

[dw10ant]

S2 Immobiliser

Pictures from under the drivers dash panel. Two boxes connected to the ignition switch and plenty of black wiring with several fuses wrapped up with black insulation tape suggests an aftermarket fitment but both boxes appear to be of Audi origin.
I was expecting to find the wiring diagrams for the immobiliser on http://www.s2central.net/S2_Schematics/MY95-ABY-C.htm
but section C54 for the immobiliser and anti-theft are not accessible and shown as 'Private viewing only'.
Any assistance appreciated. The immobiliser and central locking were not utilised when we built LYT4X from a bare shell.
Confirm that the alarm goes off as soon as the battery is connected and the ignition switch is bypassed. No instrument panel lights and no output to the starter motor solenoid.
Found the following which may assist.
http://www.clubgti.com/showthread.ph...ith-this-alarm

http://www.vwaudiforum.co.uk/forum/showthread.php?40761-The-alarm-central-unit-998-VAG-153

[andy10v]

I think that is a Scorpion alarm for Audi, if so if the battery is removed or goes flat you need to re set the immobilizer with the key fob.

If you google "vag scorpion alarm" there are a load of threads with similar issues.

Jas11n on here had to have his removed after the battery in the alarm drained when the car was left and the alarm would would not work properly and could not be reset.

I would trace the wires from the box, confirm the intercepts/breaks and remove it, rejoining the wires.

[andy10v]

Mine had a load of wires to remove, but was not too bad once you figured out what was going on.

+feed
-earth
Cut wires at ignition switch
Cut wires underneath dash
cut into central locking
tapped into indicators?
armed light on dash
wires to siren
loads of wires between the alarm units (looked crazy but just needed removed)
wires to proximity sensor
wires to in car sensors

So most just needed cut out and removed, the wires that had been cut and the immobilizer was controlling were just rejoined.

[dw10ant]

That's the main issue here - no fobs.
Looks like I will have to do what I've done in the past when owners have lost their fobs - unwrap everything and reinstate to original loom.
As long as this whole system has been retro fitted I don't think there will be an issue. Initially I was worried in case it was factory fit and that there would be repercussions that would surface and bite me in the backside.

[andy10v]

Initially I was worried in case it was factory fit and that there would be repercussions that would surface and bite me in the backside.

I would trace the wires first confirm one does not disappear inside the ecu (eg immobilizer chip in key).

I dont know what year the ECUs got immobilizers?

ECU immobilizer can be removed when the ECU is chipped.

[dw10ant]

Thanks for that. I will try and get back to it in the next couple of days but otherwise may be done on Sunday when it's quiet and no customers to interupt.

[andy10v]

Yeah, its just one of those pish jobs.

The immoblizer cars have a reader ring on the ignition switch. You can also bypass the ecu immobilizer by fitting an non immobilizer ecu.

Its a 95/96 car with a home fry ECU I think?

[mackenzie50]

Thanks for the input Andy, to help Dave with sorting my alarm/immobiliser out.
Btw, I understood on purchase that the Ecu has had a 'homefried' boost chip(to about 280bhp) installed..is that S2.central's expertise?

[andy10v]

Yup, homefried ecu is done by S2central (Paul N), both chips are replaced, you have higher boost, and fuel/timing to match.

I think 95 was when S2s started getting immobilizers?

Immobilizer ECU has a B suffix.

[mackenzie50]

Ta