CX Immobiliser Reset

[Ianrob123]

Help! - I have just bought a 1989 CX 25 GTI Turbo 2 (a month or so ago) – and my son was playing with the immobiliser key pad – and has managed to now immobilise the car! – The previous owner has no idea what the code is, and actually assumed that it was disconnected. Has anybody got any idea on what I can do, so that I can reset it, and start the car?!

[xantia_v6]

My guess is that the immobiliser was disabled. I think that this was possible on the CX and early XM by setting the code to 0000.

If your son has managed to set a new code, then the only approved way to unlock it is to type in the same code.

If that is not possible, then you will have to get the immobiliser reprogrammed by having the memory chip removed from the ECU and reprogrammed to a known code. The trick is finding someone who is familiar with the ECU who can do it. Or find a replacement ECU with known code.

[white exec]

Hi, welcome, and congratulations on acquiring the CX.

The owner's handbooks usually have a section that deals with the immobiliser, and the options for operating it.
Entry of repeated incorrect codes do (on some versions) lock you out for increasingly lengthy periods of time.

If you get really stuck, make contact with John (xmexclusive) on club-xm.co.uk, who is a guru on these immobilisers, and has helped many owners. As Mike says, an '89 CX likely to have overlap with early ('89?) XM.

[white exec]

We happen to have the Citroen CX (Series 2) workshop manual available here.
Go to Board Index > Members' Area*** > Resources > Citroen Mechanics Handbooks [right at the top]
In the table, look for CX (Series 2) Manual

Click on it to download the pdf.
Go to the Electrics section, and there is the complete circuit diagram for the car, along with component numbers listing.

#142 = injection ECU
#734 = injection relay
#731 = fuel injection electronic relay

Those last one/two do the same job as the double "Bitron" relay on XMs and many later cars, and have a role in permitting engine starting according to input from the keypad and the injection ECU. Similar, but not identical to, XM.

*** This forum area is available to Donating members. Use the link below to make the small donation needed...

A response to your question by a forum admin will require detailed vehicle information that requires you to have made a current contribution to the Forum.

Donate Further Information

A few other CX items there too.
Hope helpful.