Circuit 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 enable 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. Refer to Immobilizer System Component Programming .
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1629 Theft Deterrent Fuel Enable Signal Not Received
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The ECM has not received the fuel enable password from the RCDLR within 1 second.
Actions Taken When the DTC Sets
| • | The vehicle will not start. |
| • | The instrument panel cluster (IPC) will 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 communication problem on the serial data line between the RCDLR and ECM may cause DTC P1629 to set. This loss of communication will not allow the ECM to receive the RCDLR's fuel enable password. In this instance, a U code will also be set. To ensure proper diagnosis of the system, all U code DTCs must be corrected prior to performing DTC P1629 diagnostics.
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.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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To set this code, the password that the ECM has learned does not agree with the password being received from the RCDLR or the ECM did not received the password from the RCDLR. This condition can occur if the RCDLR has been replaced and the Programming Theft Deterrent System Components procedure has not been performed.
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If the ECM resets the DTC after the programming theft deterrent system components procedure has been performed, the RCDLR is malfunctioning.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Immobilizer Schematics | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Perform the Programming Theft Deterrent System Components procedure. Refer to Immobilizer System Component Programming . Is the procedure complete? | Go to Step 3 | -- |
Does the DTC reset? | Go to Step 4 | System OK | |
4 | Replace the remote control door lock receiver (RCDLR). Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 5 | -- |
Does the DTC reset? | Go to Step 2 | System OK | |
