DTC P1631 3.6L (LY7)
Diagnostic Instructions
DTC Descriptor
DTC P1631: Theft Deterrent Start Enable Signal Not Correct
Circuit/System Description
The remote control door lock receiver (RCDLR) sends the fuel enable password to the engine control module (ECM) via the serial data circuit. The ECM verifies the fuel enable password received matches the password stored in memory. If the fuel-continue
password is correct, the ECM enables the starting and fuel delivery systems. When replacing an ECM with a GM SPO replacement part, the new ECM will learn the incoming fuel enable password immediately upon request.
Conditions for Running the DTC
| • | DTC P1631 runs continuously once the above conditions are met for about 5 seconds. |
Conditions for Setting the DTC
The ECM remains in theft deterrent password learn mode.
Action Taken When the DTC Sets
| • | It may be impossible to start the vehicle. |
| • | The instrument panel cluster (IPC) will illuminate the SECURITY indicator. |
| • | The ECM will not illuminate the malfunction indicator lamp (MIL). |
Conditions for Clearing the DTC
| • | The history DTC clears after 40 malfunction-free warm-up cycles. |
| • | The DTC can be cleared with the scan tool. |
Reference Information
Schematic Reference
Theft Deterrent System Schematics
Connector End View Reference
Master Electrical Component List
Description and Operation
Content Theft Deterrent (CTD) Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Use the scan tool to verify that DTC P1631 is not set.
| ⇒ | If the DTC is set, the password learn procedure is required to perform. If the DTC is set again, replace the ECM. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for the ECM replacement, set-up, and programming
DTC P1631 4.6L (LH2)
Diagnostic Instructions
DTC Descriptor
DTC P1631: Theft Deterrent Start Enable Signal Not Correct
Circuit/System Description
The remote control door lock receiver (RCDLR) sends the fuel enable password to the engine control module (ECM) via the serial data circuit. The ECM verifies the fuel enable password received matches the password stored in memory. If the fuel-continue
password is correct, the ECM enables the starting and fuel delivery systems. When replacing an ECM with a GM SPO replacement part, the new ECM will learn the incoming fuel enable password immediately upon request.
Conditions for Running the DTC
| • | DTC P1631 runs continuously once the above conditions are met for about 5 seconds. |
Conditions for Setting the DTC
The ECM receives an incorrect password from the RCDLR.
Action Taken When the DTC Sets
| • | It may be impossible to start the vehicle. |
| • | The instrument panel cluster (IPC) will illuminate the SECURITY indicator. |
| • | The ECM will not illuminate the malfunction indicator lamp (MIL). |
Conditions for Clearing the DTC
| • | The history DTC clears after 40 malfunction-free warm-up cycles. |
| • | The DTC can be cleared with the scan tool. |
Reference Information
Schematic Reference
Theft Deterrent System Schematics
Connector End View Reference
Master Electrical Component List
Description and Operation
Content Theft Deterrent (CTD) Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Use the scan tool to verify that DTC P1631 is not set.
| ⇒ | If the DTC is set, the password learn procedure is required to the DTC is set again, replace the ECM. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for the ECM replacement, set-up, and programming
