Circuit Description
After the key resistor pellet has been confirmed by the Passkey portion of the Vehicle Theft Deterrent System (VTD), the Vehicle Theft Deterrent (VTD) control module sends a password to the 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 unless the VTD system has Fail-Enabled. If the VTD control module and PCM loose 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 loose its Fail-Enable status and will no longer start until communications has been reestablished. If the VTD control module and PCM loose 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 injection once it has been enabled within a given ignition cycle to prevent stalling as a result of VTD system faults.
Conditions for Setting the DTC
| • | The vehicle Theft Deterrent (VTD) system is enabled. |
| • | 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 DTC
| • | A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related failure. |
| • | PCM battery voltage is interrupted. |
| • | Using a scan tool. |
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? | -- | -- |
