VW GTi immobiliser follow up.

[Tim Lamb]

Progress so far...

I have located and stripped out the immobiliser control box. Although it looks to be an *after market* fitment it was made by VW AUDI (998 VAG 167 and BHGF) and the date '97 coincides with the R registration.

Inside the box is a printed circuit board with a fair bit of conventional electronic gismos. I can read off component part nos. if anyone is that bored:-) Strapped to the back of the board is a Ni Cad battery pack; 5 cells, rechargeable 2000 somethings.

Supply to circuit board is 12V (ignition off, I think) but battery pack only registers 2.3V or so.

Elsewhere, the fuses appear OK although I have not done more than a visual check. The relays were all properly seated but three slots are vacant. From memory 3, 7 and 10.

Relay 10 base has a fabricated brass strip linking two of the socket pins.

Still no power to the pump!

I could strip out and attempt to re-juvenate the battery cells or ?????

regards

[Jules Richardson]

That might be OK - hard to tell without tracing out a schematic and knowing what the gubbins all is. I've certainly had vintage stuff using

+5V parts that would still retain settings with standby batteries at that kind of level. You can probably work out from the ICs and the board whether it's all using logic at battery voltage, or if it's got a local DC-DC converter for a lower voltage.

Last resort, I think - it might forget something vital if you remove the batteries, assuming they aren't already "dead enough".

I'm surprised it's not all a big potted blob so that folk can't tinker with it!

cheers,

Jules

[Harry Bloomfield]

Tim Lamb wrote on 08/03/2010 :

Count the number of cells and multiply by 1.2, the result is the voltage it should be.

[Tim Lamb]

I have just spoken to a helpful gentleman at Scorpion Alarms who explained that the bit I have stripped is only the siren and the rest is tucked away behind the glove compartment.

Stripping and re-connecting is said to be *easy* so we'll see.

regards

[js.b1]

Are you sure there is no bypass switch?

- Very often there is a momentary push-button switch hidden somewhere, eg, under the passenger kickpanel. That would reset the alarm and disable any immobiliser.

- Alternatively a shunt over the immobiliser, although some systems had 3-4-5 immobilisation points.

Beware sticking probes into wires, it is a good recipe for kinking the conductors for damp/short later on. A favourite of the "cut-n-twist-n- tape" alarm installers who should be strangled.

[Tim Lamb]

In message , js.b1 writes

No.

I'm not sure I would ever want to own a GTi either. Lots of posts on the forums whinging about no alarm = no insurance!

This is a Scorpion 5000 system and apparently has 3 immobilisation points:-(

I now have the full system dangling into the footwell. When I get some more brain cells activated I'll try to see which wires go where.

regards