Where is the immobilizer module?
 

Hi,
Can anyone tell me where this is? Also, assuming it is a stand alone unit can it be replaced without a software download? Still fighting the problem of the occasional no start and flashing immobilizer light and thinking the module may be cooked.

Immobiliser function is an integral part of the CEM and ECM. There is no separate module.

Lovely, ok thank you.

Don't know where it is, but it may look something like this https://www.ebay.co.uk/itm/Volvo-S40...kAAOSwcaBcL6JJ

That is it and it is mounted under the dash above the instrument cluster.

Remove the instruments and look up under the dash, it is quite clearly visible sitting on a ledge.

Ah - right. I knew I had seen it somewhere! Thank you.

How does immobilizer work?
 

HI,
My V40 refuses to start now and than.At that moment I can see the crossed out car icon lights up.
Now I try to understand how the immobilizer works.
Suppose It works as follows: Key sends a signal that is picked up by the antenna around the contact. If it is the right key the immobilizer recieves the right code and sends a OK code to the cpu witch release the starting relay ant the motor crancks.Am i right?
If I want to change the immobilizer but keep the key and antenna does this work?:confused_smile:

The immobiliser module is paired with the ECU and the key. The key is not linked to the antenna ring in any way, as the antenna is just a few wires receiving and sending the signal to the immobiliser/ECU.

First thing to try, would be to replace the antenna ring, just in case it is faulty. If that does not work, then you might have a problem with the immobiliser module. Only way I can think of in that case, is to get a new immobiliser module and get it paired with the key and ECU at a volvo dealership. The only other option is to get a complete ECU lockset from a donor car with the exact same engine and swap everything over. The ECU lockset includes the ECU, immobiliser module, key, steering column lock barrel, drivers door lock, boot lock and glovebox lock. Also, in case you have the later post mid 2002 flip key that incorporates the key and fob together, you will also need the lock alarm module which is located undder the stereo and receives the fob signal for locking/unlocking the car

If for any reason the replacement immobilser (programmed at Volvo), or the complete lockset replacement does not solve the problem, then there is a possibility that there is a wiring problem, either an earth issue with the ECU or most probably corroded wires under the radiator or under the driver's wing