B2723

DTC B2723 Pass-Key (R) II Detection Circuit Shorted To Voltage/Open:

DTC B2723 Pass-Key (R) II Detection Circuit Shorted To Voltage/Open (Part 1 Of 2):

DTC B2723 Pass-Key (R) II Detection Circuit Shorted To Voltage/Open (Part 2 Of 2):

CIRCUIT DESCRIPTION
The Personal Automotive Security System (PASS-Key(R) II) is a vehicle theft deterrent system. The PASS-Key(R) II is designed to prevent vehicle theft by disabling the engine from starting unless an ignition key with a specific resistor pellet code is used in the ignition lock cylinder.

The ignition lock cylinder contains the resistor sensing contacts. These contacts touch the resistor pellet embedded in the ignition key. When the ignition key is infested in the ignition lock cylinder, the resistor pellet completes the key detection circuit (circuits 1073 and 1074).

When the ignition switch is turned from the LOCK or OFF to the RUN position, the Body Control Module (BCM) applies a 5V reference voltage to circuit 1073. Then, the BCM reads the resistor pellet code and compares the stored resistor pellet code against the ignition key resistor pellet code for a correct match.

Upon detecting a correct match, the BCM sends a fuel enable password to the Powertrain Control Module (PCM) through the Class II serial data link. As a result, the PCM enables the theft deterrent relay, and allows fuel delivery to the engine.

CONDITIONS FOR SETTING THE DTC
^ The voltage detected in circuit 1073 by the BCM is high, indicating that a short to B+ 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
^ The BCM stores DTC B2723 in memory.
^ The BCM sends a message to the Instrument Panel Cluster (IPC) to turn on the SECURITY indicator through the Class II serial data link.
^ In addition, the BCM takes 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.
- Dirty key resistor pellet.
- Open key resistor pellet.
- An intermittent open or short to B+ in circuit 1073 or circuit 1074.
- Open in the ignition cylinder key contacts.
- Poor connections at the BCM or ignition lock cylinder.
^ 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 this DTC.
^ Open or short to B+ 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 reappear.
^ DTC P 1626 will set in the Powertrain Control Module (PCM) when the ignition switch is in the RUN position with the BCM disconnected. When BCM diagnostics and repairs are completed, refer to the Engine Controls for additional information on PCM related DTCs. Powertrain Management

TEST DESCRIPTION
Numbers below refer to the Step numbers on the diagnostic table.
2. Checks if the PASS-Key(R) II resistor pellet is within the allowable range.
3. Determines if the BCM output voltage to the ignition lock cylinder is within the proper range.
4. Checks for an open in circuit 1073.
10. Checks for a short to B+ in circuit 1073.
12. Checks for an open in circuit 1073.
14. Checks for a short to B+ in circuit 1074.
16. Checks for an open in circuit 1074.