Passlock System Check

Circuit Description
- The Passlock TM system is designed to prevent vehicle operation if the correct ignition key is not used to start the vehicle. The ignition key will allow the lock cylinder to turn, which allows the Passlock TM sensor (located inside of the ignition switch assembly) to send an analog voltage code to the Body Control Module (BCM). If the BCM receives the correct analog voltage code from the Passlock TM sensor, then the BCM will send a Class 2 message to the Powertrain Control Module (PCM) / Vehicle Control Module (VCM) which will enable fuel delivery.
- The Body Control Module (BCM) supplies a 12 Volt supply voltage, a data line, and a ground circuit to the Passlock TM sensor.
- For additional information on the security telltale, refer to Typical Scan Tool Data Definitions, Security Lamp State, for more information.

Diagnostic Aids
You must diagnose the Diagnostic Trouble Codes in the order specified in the Passlock TM System Diagnostic Trouble Code List. Failure to do so may result in the following:
- Extended diagnostic time.
- Incorrect diagnosis.
- Incorrect parts replacement.




Test Description
1. This test checks for a malfunction related to the IPC preventing the SECURITY telltale bulb check. If this malfunction is due to an open GAUGES fuse, the SECURITY telltale will not turn ON and the engine will not run.
2. The SECURITY telltale will turn ON and stay ON when the ignition switch is in RUN and there is a currently detected a Passlock TM DTC.
3. This test checks for a Tamper condition. The engine will not be allowed to run while the SECURITY telltale is flashing and the Tamper Timer is running. Refer to Typical Scan Tool Data Definitions, Tamper Timer for more information.
4. This test checks for a malfunction which prevents communication between the IPC and the BCM. This condition will also cause the SECURITY telltale to remain ON when the ignition switch is turned to OFF.
8. The operation of the SECURITY telltale indicates that Passlock TM DTCs exist. If the scan tool is operating properly and indicates that there are no Passlock TM DTCs, the BCM may be malfunctioning.
9. This condition, along with the powertrain parameter VTD Fuel Disable displaying ACTIVE during or immediately following cranking, indicates an open in the Passlock TM sensor circuits. This condition is tested in the DTC B2958 diagnostic table.
11. When the SECURITY telltale successfully completes the bulb check and the engine starts and runs properly, the Passlock TM system is operating correctly with no malfunctions present.