The remote control door lock receiver (RCDLR) sends the start enable password to the engine control module (ECM) via the serial data circuit. The ECM verifies the start enable password received matches the password stored in memory. If the start enable password is correct, the ECM enables the starting system. When replacing a ECM with a GM SPO replacement part, the new ECM will learn the incoming start enable password immediately upon receipt.

This diagnostic procedure supports the following DTC:

DTC P1632 Theft Deterrent Start Disable Signal Received

The ignition is ON.

The ECM receives a start disable message from the theft deterrent module (TDM).

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 start 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. Refer to Programming Theft Deterrent System Components .

The numbers below refer to the step numbers on the diagnostic table.

3. 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.

5. If the ECM resets the DTC after the programming theft deterrent system components procedure has been performed, the RCDLR is malfunctioning.