GM Service Manual Online
For 1990-2009 cars only

Object Number: 192130  Size: MF
Engine Controls Components
PWR, GND, and DLC
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Passlock Module receives the code from the hall effect sensor in the steering column and compares it to the code the Passlock module learned at the first power up at the factory. If this code matches the code stored in the Passlock module, the Passlock module will send a fuel continue message to the PCM (The PCM enables fuel injection temporarily until the fuel continue/disable decision is made). If the Passlock module does not send a code or if the PCM doesn't receive it, the vehicle will not start (start and stall). If the Passlock module and PCM lose communication with each other while the engine is running the Passlock module will Fail-Enable and allow the driver to restart the vehicle on future ignition cycles until communication between the Passlock module and PCM are restored. If the battery is disconnected during this period, the vehicle will lose its Fail-Enable status and will no longer start until communications has been reestablished. If the Passlock module and PCM lose communications with each other while the engine is not running, the Passlock system will disable fuel until communication is restored to prevent vehicle theft. In both cases DTC P1626 will be set. The PCM will not disable fuel injection once it has been enabled within a given ignition cycle to prevent stalling as a result of Passlock system faults.

Conditions for Running the DTC

    • The vehicle Theft Deterrent (VTD) system is enabled.
    • The fuel enable decision point has been reached.

Conditions for Setting the DTC

    • The system has Fail-Enabled due to a loss of communications while the engine is running.
        OR
    • No password (code) message is received by the PCM from the Passlock control module prior to the VTD Fuel Decision Point.

Action Taken When the DTC Sets

    • The vehicle will not start.
    • The malfunction indicator lamp (MIL) will not illuminate.

Conditions for Clearing the DTC

    • A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures
    • The use of a scan tool.

Diagnostic Aids

The most likely cause of DTC P1626 is a loss of serial data communication to the Passlock module. Check for loss of power to the Passlock module or for other causes of communication loss. Use the Class 2 Circuit Check in the scan tool to determine if the Passlock module is active (Class 2 Message Monitor on the scan tool). Refer to Diagnostic System Check - Theft Deterrent for further diagnosis.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing DTCs use the scan tool Capture Info to record freeze frame and failure records for reference, as data will be lost when clear Info function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

Go to Powertrain On Board Diagnostic (OBD) System Check