GM Service Manual Online
For 1990-2009 cars only

The scan tool readings of the theft deterrent 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
    • Battery/ignition inputs
    • Basic 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 is for assembly plant use only.

Data

Ignition 1 - Range: ACTIVE/INACTIVE: 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: 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 to the Passlock. Power is active whenever the BCM is awake. 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, the Passlock power will turn off for approximately 0.1 seconds to reset the Passlock sensor and perform internal diagnostics.

Passlock™ Data Voltage - Range: 0-5 Volts: The Passlock™ data voltage displayed indicates the voltage code from the Passlock sensor to the BCM. The BCM determines if the voltage received is a valid code or an invalid code. The BCM has 10 valid voltage window codes, 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 reads this analog voltage and sends a class 2 password 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.

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 code or an invalid code. The BCM has 10 valid codes, an OPEN code, a TAMPER code, and a SHORTED code. The scan tool will display any valid 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 voltage. The tamper timer has a delay of approximately 10 minutes. The vehicle will 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 code from the Passlock™ sensor. The learn procedure consists of 3 consecutive periods of approximately 30 minutes. The auto learn timer does not display the time in which the PCM/VCM is in the tamper mode.

Security Lamp State - Displays: ON/OFF/FLASHING: 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.