System Operation

The PASS-Key II system is designed to prevent the engine from starting if the proper resistance is not sensed from the ignition key. Of the 15 key codes (resistance values) available, only one will work with each BCM. Once the key code is programmed into the BCM, the resistance value is stored in a non-volatile memory.

The PASS-Key II system prevents the engine from stating by controlling the theft deterrent relay and the PCM fuel enable input. If the PCM does not sense the proper frequency signal on the fuel enable input, it will not provide fuel to the engine.

If the wrong resistance value is sensed when the ignition switch is in the "RUN" position, the BCM will not ground the starter enable circuit and will not output the fuel enable signal for approximately three minutes. This prevents the engine from starting and discourages the thief from trying key codes (resistance values) at random.

If the correct resistance value is sensed when the ignition switch is in the "RUN" position, the BCM will ground the starter enable circuit and output the fuel enable signal. This will allow the engine to start normally.

If the PASS-Key II system detects an open or short to ground when the ignition switch is in "RUN" position, the BCM will default to fail enable. Fail enable occurs when the proper key resistance has been sensed before the open or short to ground occurs. Fail enable will illuminate the security indicator lamp and allow the operator to stop and start the vehicle until the problem is corrected.