Kind of an odd question but is the key programmed to the immobilizer or ECU? Also, conversely, if memory is correct the immobilizer is programmed to the ECU, correct?

 

The immobilizer system includes the
• Immobilizer system keys (two master keys and one valet key at new vehicle delivery)
• Immobilizer system indicator -- display light
• Immobilizer control unit-receiver -- ECU
• Engine control module (ECM)/powertrain control module (PCM)

Data stores are at BOTH the ECU and ECM/PCM -- in fact, the two need to be synchronized