B2723

DTC B2723 Pass-Key (R) II Detection Circuit:

DTC B2723 Pass-Key (R) II Detection Circuit (Part 1 Of 2):

DTC B2723 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 B2723 when it cannot read the ignition key resistance value due to a short to voltage or an open in circuit 1073, or circuit 1074.

CONDITIONS FOR SETTING THE DTC
^ Voltage level sampled at the BCM's PASS-Key (R) II input circuit is high, signaling that an invalid PASS-Key (R) II resistance was detected, and a short to voltage, or an open circuit is present.
^ Condition must be present during an engine start attempt, or for 1 second anytime after the engine has started.

ACTION TAKEN WHEN THE DTC SETS
^ Stores a DTC B2723 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 or circuit 1074 is either open or shorted to voltage 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 or circuit 1074 is either open or shorted to voltage 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 B2723 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
^ The following conditions may cause an intermittent malfunction to occur:
- Dirty or loose ignition cylinder key contacts or PASS-Key (R) II resistor.
- Open PASS-Key (R) II resistor.
- An intermittent open or short to voltage in circuit 1073 or circuit 1074.
- Open in the ignition cylinder key contacts.
- Poor connections at the BCM or ignition switch connector.
^ Make sure the key resistor contacts are clean and free of any grease, oil, etc. These substances could interfere with the key detection circuit and set a DTC.
^ If there is an open or short to voltage in circuit 1073 or circuit 1074.
^ Check for poor connections at both the BCM and the ignition lock cylinder assembly, these could cause an open, short, or incorrect PASS-Key (R) II resistance, or intermittent malfunction. 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 B2723.
2. Checks if the PASS-Key (R) II resistor pallet is within the allowable range.
3. Determines if the BCM output voltage to the ignition lock cylinder is within range.
4. Checks for an open in circuit 1073.
10. Checks for a short to voltage in circuit 1073.
12. Checks for an open in circuit 1073.
14. Checks for a short to voltage in circuit 1074.
16. Checks for an open in circuit 1074.