GM Service Manual Online
For 1990-2009 cars only

The scan tool readings of the Passlock™ system assist in diagnosing a problem.

The typical scan tool data definitions represent general information displayed on the scan tool regarding the following information:

    • Passlock™ system functions
    • Ignition inputs
    • Basic Passlock™ operating conditions

The following data messages and the menu headings are displayed on the scan tool:

Module Information

Security Calibration Number - Displays: 16XXXXXX: This information refers to the security calibration part number in the body control module (BCM).

Security Suffix - Range: AA-ZZ: This information refers to the security calibration identification number in the BCM.

Module Part Number - Range: 16XXXXXX: This information refers to the part number assigned to the BCM currently in the vehicle.

Manufacturers Enable Counter - Range: 0-255: This information refers to the actual value for the Manufacturer's Enable Counter (MEC) in the BCM. This information is for assembly plant use only.

Data

Ignition 1 - Range: ACTIVE/INACTIVE: The BCM uses this data in order to determine the position of the ignition switch. When the ignition switch is in the RUN or CRANK position, ACTIVE is displayed. When the ignition switch is not in the RUN or CRANK position, INACTIVE is displayed.

Ignition 3 - Range: ACTIVE/INACTIVE: The BCM uses this data in order to determine the position of the ignition switch. When the ignition switch is in the RUN position, ACTIVE is displayed. When the switch is not in the RUN position, INACTIVE is displayed.

Battery Voltage - Range: 9.0-16.0 Volts: The voltage value displayed refers to the battery system voltage measured by the BCM on CKT 1140.

Passlock™ Power - Range: ACTIVE/INACTIVE: The BCM supplies 12 volts and a ground for the Passlock™. The Passlock™ power is active whenever the BCM is awake. After the ignition switch is turned to the OFF position, the BCM may require up to 20 minutes in order to power down. When the ignition switch is turned to the OFF position, a momentary loss of voltage may occur at the Passlock™ sensor. This occurrence is normal due to the BCM internal self test when the ignition switch is turned to the OFF position.

Passlock™ Data Voltage - Range: 0-5 Volts: The Passlock™ data voltage displayed indicates the return voltage from the Passlock™ sensor to the BCM. The BCM also determines if the voltage received is a valid voltage window or an invalid voltage window. The BCM has 10 valid voltage windows, an OPEN voltage window, a TAMPER voltage window, and a SHORTENED voltage window. The value displayed on the scan tool will be within 0.0-5.0 volts. The BCM converts this analog voltage to a class 2 serial data password. The password is then sent to the PCM/VCM. The PCM/VCM must receive the same password that was learned in the last learn procedure. If the PCM/VCM does not receive a valid password from the BCM, the PCM/VCM will not enable the fuel injection system. Refer to PASSLOCK Reprogramming Seed and Key (10 minutes), or PASSLOCK Reprogramming Auto Learn (30 minutes).

Passlock™ State - Displays: IGNITION OFF/TAMPER/FAIL ENABLE/FAIL ENABLE DEC/SEEDKEY LRN PEND/SEEDKEY LEARN/AUTO LEARN PEND/LEARN PASSLOCK/MONITOR PASSLOCK/NORMAL DECISION/AUTO LEARN: The display refers to the state of the Passlock™ system.

Passlock™ Code - Range: OPEN/SHORTED/TAMPER/NUMERIC: The Passlock™ code displayed indicates the internal Passlock™ sensor resistance value. The BCM determines if the Passlock™ code received is a valid Passlock™ code or an invalid Passlock™ code. The BCM has 10 valid Passlock™ codes, an OPEN Passlock™ code, a TAMPER Passlock™ code, and a SHORTED Passlock™ code. The scan tool will display any valid Passlock™ code as a numeric value. The value displayed on the scan tool should be within 1-10 (i.e. valid code 7), SHORTED, TAMPER or OPEN.

Tamper Timer - Range: 0-600 Seconds: Use the tamper timer as part of the interactive procedure in order to allow the BCM to display the time remaining when in the tamper mode. The tamper timer starts when the ignition switch is turned to the RUN position and the BCM receives a Passlock™ data voltage that is different from the last learned Passlock™ data voltage. The tamper timer has a lockout timer of approximately 10 minutes. The vehicle must remain in the tamper mode even if the ignition switch is turned from the RUN position to the OFF position during the 10 minute period.

Auto Learn Timer - Range: 0-600 Seconds: Use the auto learn timer as part of the interactive procedure in order to allow the BCM to learn valid Passlock™ data from the Passlock™ sensor. The learn procedure consists of 3 consecutive lockout cycles of approximately 30 minutes. The auto learn timer does not display the time in which the PCM/VCM is in the lockout mode.

Security Lamp State - Displays: ON/OFF/FLASHING: The security lamp will turn ON steady for 3 seconds and then turn OFF when the ignition switch is turned from the OFF position to the RUN position. The security telltale should have 3 states: OFF, ON STEADY and FLASHING. If the IPC is unable to communicate with the BCM, the security telltale will stay ON STEADY (after the bulb check). The Passlock™ system will function while the IPC is not communicating, as long as class 2 communication is possible. If the vehicle is in the lockout cycle, the security telltale flashes momentarily and then turns ON STEADY for approximately 10 minutes. The Passlock™ system requires 3 consecutive lockout cycles in order to complete the 30 minute Auto Learn procedure for a changed component, refer to PASSLOCK Reprogramming Auto Learn . A 10 minute Seed and Key learn procedure is also available, refer to PASSLOCK Reprogramming Seed and Key .