Ok, well your key doesn't have a transponder in it, so we aren't dealing with SKIM here, if you could post a picture of your ECU (PCM) and possibly the part number I can look up what we might be dealing with here.
Symptoms were just as described in SKIM failure. Runs for 3 secs then shuts down. The security module was replaced about 11 years ago. This car has been mine since it was 3 years old. I believe the security is the same as the US model just the signal is sent via fob not transponder key. The 96 ecu fixed the security problem as they don't have the feature. The waiting list for the module is 2 years according to jeep Australia and costs about $1500. When they replaced it under warranty the first time I was told it was in the passenger door (I think) my mechanic has pulled the door skin and can't find anything of the sort. The receiver for the fob is in the overhead console. I have found that and it works the keyless entry but I'm not sure if the security module is also incorporated into it.
sorta... Once the security option is activated in the PCM it cannot be un-done.
you might clip and tape off the CCD bus wires from the RKE so it cant talk to a new PCM... shouldn't disable the RKE portion as that is hard wired to the door lock module.
the CCD bus are two wires that all the modules in the car communicate with... stands for "Chrysler Collision Detection", though it has nothing to do with physical collisions like an accident.
should be a violet/brown wire and a white/black wire. they will be in the harness as a twisted pair.
In the UK the may and scofield immobiliser is located in front of your right knee in the drivers side. Remove plastic trim under steering wheel. Not the steering column but between that and the floor. You will need to remove hood release. Behind that is a steel plate remove that too. To the right hand side is a black box with a wiring harness of all black wires. That's the immobliser.