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

Module Part Number - Range: 16XXXXXX: This information refers to the part number assigned to the Passlock™ Module 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 Passlock™ Module. This information is for assembly plant use only.

Data List

Ignition 1 - Range: ACTIVE/INACTIVE: The Passlock™ Module 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.

Battery Voltage - Range: 9.0-16.0 Volts: The voltage value displayed refers to the battery system voltage measured by the Passlock™ Module on CKT 1740.

Passlock™ Power - Range: ACTIVE/INACTIVE: The Passlock™ Module supplies 12 volts and a ground to the Passlock™ Sensor. The Passlock™ power is active whenever the battery voltage and ignition 1 are present.

Passlock™ Data Voltage - Range: 0-5 Volts: The Passlock™ data voltage displayed indicates the return voltage from the Passlock™ sensor to the Passlock™ Module. The Passlock™ Module also determines if the voltage received is a valid voltage window or an invalid voltage window. The Passlock™ Module 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 Passlock™ Module converts this analog voltage to a class 2 serial data password. The password is then sent to the VCM/PCM. The VCM/PCM must receive the same password that was learned in the last learn procedure. If the VCM/PCM does not receive a valid password from the Passlock™ Module, the VCM/PCM will not enable the fuel injection system. Refer to PASSLOCK Reprogramming Auto Learn .

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

Passlock™ Code - Range: OPEN/SHORT/TAMPER/NUMERIC: The Passlock™ code displayed indicates the internal Passlock™ sensor resistance value. The Passlock™ Module determines if the Passlock™ code received is valid or invalid. The Passlock™ Module has 10 valid Passlock™ codes, an OPEN Passlock™ code, a TAMPER Passlock™ code, and a SHORT 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), SHORT, TAMPER or OPEN.

Tamper Timer - Range: 0-600 Seconds: Use the tamper timer as part of the interactive procedure in order to allow the Passlock™ Module 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 Passlock™ Module receives a Passlock™ data voltage that is different from the last learned Passlock™ data voltage. The tamper timer has a lockout timer of 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, however the timer will reset to 0 and will start a new count.

Auto Learn Timer - Range: 0-600 Seconds: Use the auto learn timer as part of the interactive procedure in order to allow the Passlock™ Module to learn valid Passlock™ data from the Passlock™ sensor. The learn procedure consists of 3 consecutive lockout cycles of approximately 10 minutes each totaling 30 minutes. The auto learn timer does not display the time in which the VCM/PCM is in the lockout mode.

Security Lamp Feedback- Range: 0-16 Volts: The security lamp feedback voltage normally is close to 12 volts when the security lamp is OFF and close to 0 volt when the security lamp is ON. This reading shows the voltage on the security lamp driver.

Security Lamp State - Displays: ON/OFF/FLASHING: The security lamp will turn ON steady for 5 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. The security telltale will stay ON STEADY (after the bulb check) if any DTC is stored in the Passlock™ Module; if the Passlock™ Module loses battery, ignition, or both while ignition is still supplied to the security lamp; or the security lamp driver is shorted to ground. The security telltale will flash for approximately 10 minutes to indicate that the Passlock™ Module is in lockout Tamper mode during which the fuel delivery will be defaulted to Disable. The Passlock™ system requires 3 consecutive lockout cycles to complete the 30 minute Auto Learn procedure for a changed component, refer to PASSLOCK Reprogramming Auto Learn to perform this task. Another option is the 10 minute Seed and Key procedure, refer to PASSLOCK Reprogramming Seed and Key to perform this task.