Circuit Description
The PCM controls fuel injector and starter operation based on a vehicle theft deterrent (VTD) password from the theft deterrent module. When the ignition is first turned ON, the theft deterrent module sends a programmed password to the PCM. The PCM acknowledges the password and responds to the theft deterrent module that normal fuel injector and starter operation will continue. If the PCM detects an incorrect password (VTD system failure or attempted vehicle theft), DTC 1631 will set.
Conditions for Setting the DTC
| • | The PCM is detecting an incorrect vehicle theft deterrent password from the VTD system. |
| • | The conditions is present for less than 1 second. |
Action Taken When the DTC Sets
| • | The PCM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
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 non-emission related diagnostic. |
| • | A last test failed (Current DTC) will clear when the diagnostic runs and does not fail. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. |
Diagnostic Aids
DTC P1631 indicates that the vehicle theft deterrent password that the PCM has learned does not agree with the password being received from the VTD system. This condition can occur if an incorrect key is being used when attempting to start the vehicle or if the Theft Deterrent module has been replaced and the PCMs password learn function has not been enabled. If the Theft Deterrent module has been replaced, the password must be relearned. Refer to Programming Theft Deterrent System Components in Theft Deterrent.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic System Check? | -- | Go to Programming Theft Deterrent System Components in Theft Deterrent |
