B2722

DTC B2722 Pass-Key (R) II Detention Circuit:

DTC B2722 Pass-Key (R) II Detection Circuit (Part 1 Of 2):

DTC B2722 Pass-Key (R) II Detection Circuit (Part 2 Of 2):

CIRCUIT DESCRIPTION
The PASS-Key (R) II detection circuit is completed by the PASS-Key (R) II (with embedded resistor pellet) in the ignition lock cylinder. Contacts in the ignition lock cylinder mate with those on the pellet, and the Body Control Module (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 sends a password via the Class II serial data link to the Powertrain Control Module (PCM). As a result, the PCM energizes the theft deterrent relay, and allows fuel delivery to the engine.
The BCM sets DTC B2722 when it cannot read the ignition key resistance value due to a short to ground in circuit 1073.

CONDITIONS FOR SETTING THE DTC
^ Voltage level sampled at the BCM's PASS-Key (R) II input circuit is low, signaling that an invalid PASS-Key (R) II resistance was detected, and a short to ground is present.
^ Condition must be present during an engine start attempt, or for one second anytime after the engine has started.

ACTION TAKEN WHEN THE DTC SETS
^ Stores a DTC B2722 in the BCM memory.
^ Sends a message to the Instrument Panel Cluster (IPC) to turn on the SECURITY indicator.
^ In addition, the BCM will take one of two actions:
A. If circuit 1073 is shorted to ground when attempting to start the engine, the BCM will NOT send a message to the PCM to enable the theft deterrent relay, and to deliver fuel to the engine. The vehicle will exhibit an engine no crank condition, OR
B. If circuit 1073 is shorted to ground after the engine has started, the BCM enters a fail-enable mode. Upon subsequent engine start attempts, the BCM will send a password message to the PCM via the Class II serial data link to enable the theft deterrent relay, and to deliver fuel to the engine. The engine will start.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC B2722 clears when the BCM detects a valid PASS-Key (R) II resistance value on the PASS-Key (R) II input circuit (circuit 1073).
^ A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
^ Using a scan tool.

DIAGNOSTIC AIDS
^ Check for a short between circuit 1073 and circuit 1074, or a short to ground in circuit 1073.
^ The following conditions may cause an intermittent malfunction to occur:
- Shorted PASS-Key (R) II resistor or ignition key cylinder contacts.
- An intermittent short to ground in circuit 1073.
- An intermittent short between circuit 1073 and circuit 1074; the BCM would interpret this as a short to ground condition.
^ If the DTC is a history DTC, the problem may be intermittent. Try performing the tests shown while moving wiring, connectors, and the key, this can often cause the malfunction to appear.
^ DTC P1626 will set in the PCM when the ignition switch is in the RUN position with the BCM disconnected.

TEST DESCRIPTION
Numbers below refer to the Step numbers on the diagnostic table.
1. Always perform the BCM Diagnostic System Check before attempting to diagnose a DTC B2722.
2. Checks if the PASS-Key (R) II resistor pallet is within the allowable range.
3. Checks for a short to ground on the ignition lock cylinder and its pigtail circuit.
4. Checks for a short to ground in circuit 1073.
5. Checks for a short between circuit 1073 and circuit 1074, which the BCM would interpret this as a short to ground.