Diagnostic Aids
- The following conditions may cause an intermittent: Intermittent open or short to ground in circuit No. 1073 (White/Black wire) or No. 1074 (Purple/White wire) between BCM and ignition switch; poor connections at BCM or ignition switch; incorrect PASS-Key(R); or dirty or loose ignition lock cylinder key contacts or PASS-Key(R) resistor.
- If key resistor pellet is incorrect, there will be no BCM outputs to theft deterrent relay or PCM for about 3 minutes. If a key (even a proper PASS-Key(R)) is inserted or ignition is turned on again, 3-minute time-out period will reset. If battery is disconnected, time-out period will be reset when battery is reconnected.
- Though it is unlikely, DTC B2721 may set due to extremely hot or cold ambient temperatures. To eliminate this possibility, perform tests with vehicle and key at room temperature.
- Clean key resistor contacts thoroughly. Check for poor connections at BCM and ignition lock cylinder. A poor connection may cause an open, an incorrect PASS-Key(R) resistance or an intermittent malfunction.