Circuit Description
After the Passlock Sensor Resistor has been confirmed by the Passlock portion of the vehicle theft deterrent system (VTD), the VTD control module sends a password to the powertrain control module (PCM) via the Class 2 Serial Data Bus. If this password matches the password stored in the PCM, fuel will be enabled. If the VTD control module does not send a password or if the PCM doesn't receive it, the vehicle will not start or start and stall unless the VTD system has been Fail-Enabled. If the VTD control module and PCM lose communication with each other while the engine is running the VTD system will Fail-Enable and allow the driver to restart the vehicle on future ignition cycles until communications between the VTD control 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 VTD control module and PCM lose communications with each other while the engine is not running, the VTD system will disable fuel until communications is restored to prevent vehicle theft. In both cases DTC P1626 will be set. The PCM will not disable fuel once it has been enabled within a given ignition cycle to prevent stalling as a result of VTD system faults.
Conditions for Running the DTC
The vehicle theft deterrent (VTD) system is enabled.
Conditions for Setting the DTC
| • | The fuel enable decision point has been reached. |
| • | The system has Fail-Enabled due to a loss of communications while the engine is running. |
| OR |
| • | No password message is received by the PCM from the VTD 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 MIL/DTC
| • | The PCM will turn the MIL off after 3 consecutive trips without a fault condition. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures. |
| • | The scan tool Clear Info function was used. |
Diagnostic Aids
The most likely cause of DTC P1626 is a loss of serial data communication to the VTD control module. Check for loss of power to the VTD control module or for other causes of communication loss.
The PCM enables fuel on future ignition cycles only if the failure occurred when the engine was running.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | -- |
