GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 GTO 🢒 DTC 🢒 DTC P1631

Circuit Description

This test inspects for mismatched passwords between the powertrain interface module (PIM) and powertrain control module (PCM). Whenever replacing the PIM or PCM, follow the Theft Learn procedure for the system to learn the new password. This is a type C DTC.

Conditions for Running the DTC

The ignition is on and the PCM is waiting for the correct password.

Conditions for Setting the DTC

The PCM detects an incorrect password from the PIM.

Action Taken When the DTC Sets
    • The PCM stores the DTC information into memory when the diagnostic runs and fails.
    • The Check Powertrain malfunction indicator lamp (MIL) will not be activated.
    • The PCM records the operating conditions at the time the diagnostic fails.
    • The PCM stores this information in the Failure Records.
    • The engine cranks but may not start.
    • The multifunction display (MFD) in the Instrument panel, will display a message at key-on and key-off.

Conditions for Clearing the MIL/DTC
    • A Last Test Failed (current DTC) clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • Use Tech 2 to clear the DTC.

Diagnostic Aids

Remove any debris from the PCM module connector surfaces before servicing the PCM module.

The PCM in learn mode is a DTC for the personnel at the assembly plant, retailer, or outside garage as an indication that the system enables the learn mode. This means the PCM is now ready to learn a new password from the PIM while in the learn mode. When this occurs, the vehicle is vulnerable to vehicle theft.

If using Tech 2 and TIS for password linking, refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System for the linking procedure. This Tech 2 operation will take approximately 2 minutes to perform. If no Tech 2 and TIS is available, the following DTC P1631 diagnostic table must be followed.

Test Description

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

  1. The time criteria is a minimum required amount of time. The time limit can exceed this limit without interfering with the Auto Learn Procedure.

    2.

  2. If DTC P1631 is set, this indicates that you did not follow the procedure correctly. Perform the Re-learn procedure again.

Step

Action

Yes

No

Schematic Reference: Theft Deterrent System Schematics

1

Was the Diagnostic System Check - Engine Controls performed?

Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls

2

  1. Inspect for any theft deterrent body control module (BCM) or powertrain interface module (PIM) DTCs being set before proceeding with this table. If a BCM or PIM DTC is set, refer to the appropriate DTC.
  2. Maintain the battery voltage while the powertrain control module (PCM) is in the Learn Procedure. Follow this procedure exactly as indicated or you will have to repeat the procedure from the beginning.
  3. Performing the following procedure causes a DTC P1630 to set when you complete the procedure. This is the intended functionality. When P1630 sets, turn OFF the ignition for 30 seconds, then turn ON the ignition and P1630 clears. If the DTC P1630 does not clear, go to the DTC P1630 table.
    4. • Turn the ignition ON, leaving the engine OFF, for 3 hours and 10 minutes.
    • Turn the ignition OFF for 30 seconds.
    • Turn the ignition ON, leaving the engine OFF, for 1 hour and 10 minutes.
    • Turn the ignition OFF for 30 seconds.
    • Turn the ignition ON, leaving the engine OFF, for 1 hour and 10 minutes or until DTC P1630 sets.
    • Turn the ignition OFF for 30 seconds.
    • Turn the ignition ON, leaving the engine OFF, for 1 hour and 10 minutes.
    • Turn the ignition OFF for 30 seconds.
    • Turn the ignition ON, leaving the engine OFF, and wait 30 seconds.
  4. Attempt to start the engine.

Does the engine start and operate normally?

Go to Step 3

Go to Step 4

3

Monitor all DTC status parameters and note any additional DTCs before Clearing DTCs.

  1. Clear the PCM DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Attempt to start the engine.

Does the engine start and operate normally?

System OK

Go to Step 4

4

Are DTCs P1626, P1630, or P1631 set?

Go to DTC List

System OK