DTC B2721: Pass-Key(R) Detection Circuit (Out Of Range): Notes

Insertion of PASS-Key(R) into ignition lock cylinder completes PASS-Key(R) circuit. Contacts in ignition lock cylinder mate with resistor pellet contacts in PASS-Key(R). BCM compares resistance value of key pellet to valid resistance programmed into BCM. When proper resistance value is read, BCM will allow theft deterrent relay to energize, steering column to unlock, and will send a message through serial data line to PCM to allow fuel enable processing to occur.

DTC B2721 will set when resistance level at BCM's PASS-Key(R) input circuit is one of 14 valid (but incorrect) resistance ranges for one second, signaling an invalid PASS-Key(R) detection. When DTC B2721 is set, the following will occur:

BCM will send signal to IPC to turn on SECURITY warning indicator.
BCM will disable theft deterrent relay.
PCM will not allow fuel enable processing to occur.
Sampling of PASS-Key(R) resistance will be disabled for a 3-minute timeout period.
An armed Universal Theft Deterrent (UTD) system will not disarm.
Steering column will remain in locked position.

DTC B2721 requires an ignition cycle to change from current to history. If conditions for malfunction no longer exist, history DTC will clear after 50 consecutive ignition cycles. DTC B2721 will also clear when conditions no longer exist, or when IPC or scan tool is used to clear codes.

NOTE: If DTC B2721 is a history code, problem may be intermittent. Wiggle wires while performing the following test.