Immobiliser won't deactivate

[EricRoberts]

Hi

I have a 1990 740 turbo estate with an immobiliser on a red fob which must be touched against a base unit on the dashboard to deactivate the immobiliser. All has been working fine until this morning when the immobiliser failed to deactivate, the red led on the dashboard continues to flash and does not go green as normal. I do not know if this is a factory fit unit or aftermarket, only got the car a few months ago.

The battery seems fine, have tried the deactivation process while hooked up to another battery just in case, and the contacts on the fob and base unit seem clean.

Does anyone know if this is a factory fit immobiliser and if there is any technique to deactivate it by, for example, disconnecting the battery etc.

I'm currently stuck in the Czech republic with the car just outside Prague and need to get the car going again ASAP.

Any help much appreciated

[roadcar2000]

It is probably an aftermarket fit. Had a similar problem. The only way round my problem was to remove the immobiliser and put the wireing back to original. It is more than likely mounted some where above the pedals. Remove the trim to look. Perhaps some one knows a quicker way. Good luck.

[Steve940estate]

As suggested above. The immobiliser is normally wired into the starter circuit so the ignition switch is disabled. Start by looking at the ignition switch itself and follow the wires from it and the base unit on the dash. Hopefully it's just a case of re-joining the ignition switch wires.

[gdphillips]

can you post a pic of the fob and the plug........mates an installer he may be able to help
or make......

[Diesel-do-nicely]

Originally Posted by EricRoberts

Hi

I have a 1990 740 turbo estate with an immobiliser on a red fob which must be touched against a base unit on the dashboard to deactivate the immobiliser. All has been working fine until this morning when the immobiliser failed to deactivate, the red led on the dashboard continues to flash and does not go green as normal. I do not know if this is a factory fit unit or aftermarket, only got the car a few months ago.

The battery seems fine, have tried the deactivation process while hooked up to another battery just in case, and the contacts on the fob and base unit seem clean.

Does anyone know if this is a factory fit immobiliser and if there is any technique to deactivate it by, for example, disconnecting the battery etc.

I'm currently stuck in the Czech republic with the car just outside Prague and need to get the car going again ASAP.

Any help much appreciated

Join the AA , they will help

[EricRoberts]

Thanks for all the helpful suggestions, attached are photos of the key fob and dashboard "dock" unit as requested

Joining the AA is my last resort... money is very tight so I want to exhaust all other options first.

[Steve940estate]

Immobilisers are great things aren't they ! It's a shame there are so many really poor quality ones about, stops anyone nicking your car though !

I expect most of the wiring will be visable if you remove the panel under the dash. Most likely lots of scotchloks and similar nastys. Hope you get it started.

[Diesel-do-nicely]

Originally Posted by EricRoberts

Thanks for all the helpful suggestions, attached are photos of the key fob and dashboard "dock" unit as requested

Joining the AA is my last resort... money is very tight so I want to exhaust all other options first.

Does the immobiliser have its own fuse ? i used to tuck the golf ones beside the fuse board, will probably be in a opaque plastic holder like a small pen.
if not then
1/Turn the car on with the ignition key, if the starter motor wont turn , then try with a length of wire, connect the spade terminal on the starter motor relay to the battery positive for 2 seconds. If it turns over and starts fine.
It is just a simple starter circuit immob.
2/If it turns over but does not start, SNIFF the exhaust pipe, if it is petrol smell then it is a spark immob.
connect the positive side of the ignition coil to the battery positive, repeat *1* and hope it goes
3/ If it still wont go, ie no petrol smell in exhaust when turning over, but you have spark at plugs when connecting the ignition coil.
then it is also immobilised in the fuel pump circuit.
It will be quicker and easier to pull the ashtray out and see if the offending immobiliser is wired in series with the loom underneath the fuse board.

[roadcar2000]

The AA will not rewire or repair the Immobiliser but tow you to a garage.

[EricRoberts]

Thanks for the additional feedback, managed to tow the car to a local garage where they are going to attempt to remove the immobiliser altogether, which suits me fine. Hopefully they will complete that work today.

Did try short circuiting the starter but with no success.