Circuit Description
The theft deterrent control module 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 a ECM with a GM SPO replacement part, the new ECM will learn the incoming fuel enable password immediately upon receipt. DTC P1630 is an informational code indicating the ECM is ready to learn the fuel enable password.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1630 Theft Deterrent Learn Mode Active
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The ECM remains in theft deterrent password learn mode for more than 2 seconds.
Actions Taken When the DTC Sets
| • | The ECM sends a serial data message to the instrument panel cluster (IPC) to illuminate the SECURITY indicator. |
| • | The ECM will not illuminate the malfunction indicator lamp (MIL). |
Conditions for Clearing the MIL/DTC
| • | A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
A GM SPO replacement ECM is in a functional state to learn the password from the theft deterrent control module. If the theft deterrent control module is replaced, the ECM must be placed in password learning mode to relearn the new password. Once learned, the password becomes permanent information that remains in the ECM. The loss of ECM battery or ignition voltage does not affect the programmed password information. Refer to Immobilizer System Component Programming .
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Theft Deterrent System Schematics Connector End View Reference: Theft Deterrent System Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | ||
