GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1999 🢒 Shelby Series 1 🢒 Engine 🢒 Engine Controls - 4.0L 🢒 DTC P1631 Theft Deterrent Start Enable Signal Not Correct

Circuit Description

This diagnostic tests for mismatched passwords between the passlock module and the PCM. Whenever replacing the passlock module or the PCM, follow the theft learn procedure in order for the system to learn the new password.

Conditions for Running the DTC

Mismatched passwords between the passlock module and the PCM

Conditions for Setting the DTC
    • The PCM detects a wrong password from the passlock module.
    • The fuel disable lockout is set.
    • The system has received an incorrect fuel continue password.
    • An invalid ignition key or malfunctioning ignition switch
    • The passlock module was replaced.

Action Taken When the DTC Sets
    • The engine starts and then the engine stalls immediately.
    • The PCM stores the diagnostic trouble code (DTC) information into the memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The PCM records the operating conditions at the time during which the diagnostic fails. The PCM stores this information in the Failure Records.

Conditions for Clearing the DTC
    • A History DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • A last test failed, or current DTC, will clear when the diagnostic runs and does not fail.
    • Use a scan tool in order to clear the DTC.

Test Description

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

  1. The 11 minute and 30 second time criteria are a minimum required amount of time. The time limit can exceed this limit without interfering with the Auto Learn Procedure. Use a scan tool (VTD Auto Learn Timer equals Inactive) in order to determine when the 11 minutes has expired.

    2.

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

DTC P1631 Theft Deterrent System-Password incorrect

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Important: Inspect for any passlock module DTCs being set before proceeding with this table, except if you were sent here from PCM Replacement. If a passlock module DTC is set, refer to the appropriate passlock module DTC.

Is a Tech 2 ® available?

--

Go to Step 4

Go to Step 3

3

Important:: 

   • Maintain the battery voltage while the PCM is in the Auto Learn Procedure. Follow this procedure exactly as indicated or you will have to repeat the procedure from the beginning.
   • 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, refer to the DTC P1630 Theft Deterrent Learn Mode Active table.

  1. Turn ON the ignition leaving the engine OFF for 11 minutes.
  2. Turn OFF the ignition for 30 seconds.
  3. Turn ON the ignition leaving the engine OFF for 11 minutes.
  4. Turn OFF the ignition for 30 seconds.
  5. Turn ON the ignition leaving the engine OFF for 11 minutes or until DTC P1630 sets.
  6. Turn OFF the ignition for 30 seconds.
  7. Turn ON the ignition leaving the engine OFF and wait 30 seconds.
  8. Attempt to start the engine.

Does the engine start and operate normally?

--

Go to Step 5

Go to Step 6

4

Important: 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 the ignition ON and P1630 clears. If the DTC P1630 does not clear, refer to the DTC P1630 Theft Deterrent Learn Mode Active table.

  1. Enter the Service Programming System (SPS) using a Tech 2.
  2. Enter the vehicle information.
  3. Choose the Request Info soft key on the scan tool.
  4. Select Done.
  5. Follow the instructions on the Vehicle Set-up screen.
  6. Disconnect the scan tool from the vehicle.
  7. Connect the scan tool to the Techline terminal.
  8. At the Techline terminal, select Service Programming System (SPS) and select terminal to Tech 2 programming method.
  9. Select Done.
  10. Follow the instructions on the remaining screens.
  11. Select the Vehicle Theft Re-learn option.
  12. Select Program at the summary screen. The terminal will download information to the Tech 2.
  13. Return the scan tool to the vehicle.
  14. Connect the scan tool to diagnostic link connector (DLC).
  15. Select Service Programming from the Tech 2 main menu.
  16. Answer the prompts regarding the model year and vehicle type.
  17. Press the Theft Re-learn soft key on the Tech 2.
  18. Follow the instructions on the remaining screens.
    19. • The PCM and the passlock module will be prepared for re-learn.
    • A security timer will be on for approximately 11 minutes or until DTC P1630 sets. It is important that during the 11 minute-wait, the user keeps the scan tool connected to the vehicle.
    • When the PCM and the passlock module are prepared to re-learn, turn OFF the ignition for 30 seconds and then start the engine.

Does the engine start and operate normally?

--

Go to Step 5

Go to Step 6

5

Important:: Monitor all DTC status parameters and note any additional DTCs before clearing DTCs.

  1. Clear the powertrain control module 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 6

6

Are DTCs P1626, P1630 or P1631 set?

--

Go to the applicable DTC table

Go to Step 2