HouseCallAuto 9/22/2012If the security light comes ON with the key ON and/or while cranking, it is an immobilizer system lock-out. There is a TSB (NTB00-019) for updated Engine Control Module (ECM) and if that has already been updated, for an updated NATS immobilizer control unit. The system will need to be programmed either by a locksmith or factory scan tool.
If the wrong key is used, and the vehicle doesn't start, the immobilizer system goes into lock mode and the engine will not start. No injector pulse. If the correct key is then used, perform "escape from lock mode" for the system to let the engine start. To escape from lock mode, turn the key on and wait 5 seconds and turn the key off. Perform this procedure 3 times and then attempt to start the engine. If unsuccessful, the vehicle will need to go to the dealer for the factory scan tool to reprogram the system.