The Opel ECUs since the Corsa B are all tied to the key and transponder, and IIRC Astra G also tied to the engine. With the Corsa C and up the ECU is further tied to the speedometer.
How it works:
The key has a transponder chip in it and around the ignition barrel there is a receiver. The ECU is coded to the receiver and the chip in the key (which uses RFID). Add to that the Astra G also has a sensor on the crank (cannot be changed without opening up the engine) and the Corsa C and up have the speedometer tied in to prevent changing of the speedometer (which also coincidentally makes it quite a mission to change the ECU on those cars). All of these devices are specifically coded to the ECU, without the correct devices the ECU won't inject fuel or spark. So turning the engine or turning on the fuel pump makes no difference as the engine isn't getting petrol and isn't sparking (the two mayor functions that makes an engine run
).
Usually the check engine light will flash if you have the incorrect key, and on some of the Opels the starter motor will still turn (to no avail).
I only know the recode procedure for the Corsa B & C:
There is a security code you get when you buy the car, it's in the car book and on it is written CAR PASS. The security code needed to recode the key is written on that. Without it you can't recode that specific ECU. To recode requires a Opel Tech 2. The Opel Tech 2 for example I heard costs something like 200 000 pounds in Britain or some such and they only sell them to recognized GM dealers.
There are some other tools but reading online not all of them work for all the ECUs from Opel. Still the security code is needed. Recoding to another key is simple if you have the security code. It's all software. I think GM charge 1 hour labor to do it (like R400).
If you don't have that security code, your only option is to change everything associated with the security system. On the Corsa B it's just the ECU, transponder chip and transponder receiver. Astra G it's that + crank id. Corsa C it's that + speedo. On the Astra H (Which includes Corsa D, later model Zafira, etc) they moved to a newer CANBUS system where every electrical component is coded. In that case, the radio, the speedometer, the engine, the ABS, the air bags, everything functions on the CANBUS and require the specific ECU they were coded to and the ECU is coded to them in turn.
This system is also used by other manufacturers naturally, hence the reason that STEALING a modern car is nearly impossible (Please note a Citi Golf isn't a modern car). It's much easier to tow and strip or hijack a modern car.
Corsa B isn't that safe for example, I have a ECU + it's transponder receiver and key chip glued to that receiver. Usually takes me around 10-15minutes to change out the ECU and everything and then the car will start with any key. I use it for testing purposes btw
But later models it starts getting very tricky. There aren't so far as I know any hacks or back doors on these systems (even the Corsa B there isn't a way around it), can't speak for other manufacturers tho but it wouldn't make sense to publish the info needed to bypass these systems as they are trying to sell a product.
Stealing a car with Dicktator in comparison requires only breaking the steering lock. Because Opel uses 60-2 timing wheel, I only really know the Dictator 60-2 but on that I could start the car within 1 minute (probably less) VS. normal Corsa B management (easiest to steal) in which I need to remove the kick panel, loosen the ECU, loosen the steering column covers. Then swap everything out, break the steering lock and rewire the ignition wires to start the car (with practice I think this could be done in about 10-15 minutes).
Everything Opel before the Corsa B have no proper security (Astra F and earlier, record, etc.), which means stealing them is nearly as easy as stealing a car with Dicktator.
