PASS-Key Detection Circuit
Table of contents
B2721 CADILLAC Possible Causes
- Faulty Ignition Key
- Faulty Ignition Lock Cylinder
- Faulty Body Control Module (BCM)
How do I fix code B2721 CADILLAC?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Cost of diagnosing the B2721 CADILLAC code
The cost of diagnosing the B2721 CADILLAC code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
B2721 CADILLAC Description
The Body Control Module (BCM) supplies a 5 volt signal and a ground circuit for the PASS-Key® system. This allows the BCM to detect PASS-Key® resistance values. Inserting the PASS-Key® (with resistor pellet) in the ignition lock cylinder completes the PASS-Key® circuit. Contacts in the ignition lock cylinder mate with the pellet contacts. The BCM compares the resistance value of the key pellet to the valid resistance programmed into the BCM. If the proper resistance value is read, the BCM allows the following functions to occur: The theft deterrent relay to energize, The steering column to unlock and The BCM sends a message through the serial data line to the powertrain control module (PCM) to enable fuel delivery. If the resistance value is incorrect, a malfunction is present and a DTC will set.