GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Impala 🢒 DTC 🢒 DTC B3031

Circuit Description

When a body control module (BCM) is replaced, it must be programmed to accept the analog voltage signal (code) of the existing Passlock sensor. When the BCM is replaced, the service replacement BCM is programmed to accept the first Passlock code it detects. If the BCM is unable to detect a valid Passlock code, the BCM will never end the programming sequence and B3031 will continue to be set as current.

In this mode, the BCM will learn the current Passlock sensor code value.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B3031 Security System Controller In Learn Mode

Conditions for Setting the DTC
    • A new BCM has been installed and the ignition is turned to the ON position, but not rotated to the CRANK position. Once the ignition switch has been rotated to the CRANK position, the BCM will learn the Passlock code. The theft relearn procedure will need to be performed in order to make the powertrain control module (PCM) receive the correct fuel enable password.
    • The BCM is in the learn mode but does not see a valid Passlock sensor code because of a sensor or a wiring problem.

Action Taken When the DTC Sets
    • The BCM stores DTC B3031 in memory as a current DTC.
    • The BCM sends a message to the instrument cluster to illuminate the SECURITY indicator.

Conditions for Clearing the DTC
    • A current DTC B3031 changes to history when the BCM detects a valid Passlock sensor code.
    • A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.

Diagnostic Aids
    • If there is an open or short in any of the Passlock sensor circuits, the BCM will be unable to read a valid code from the Passlock sensor when the program mode is active.
    • Always diagnose all other Passlock DTCs first before diagnosing this DTC. These DTCs will affect the BCM's ability to properly read a Passlock code.
    • If DTC B3031 is set in the BCM as a history DTC, clear the DTC and recheck the system. A history DTC B3031 indicates that the BCM has successfully completed the programming mode.

Test Description

The number below refers to the step number on the diagnostic table.

  1. Tests for the proper operation of the 12-volt sensor power circuit, sensor ground circuit, and Passlock data circuit. Troubleshoot the appropriate DTC prior to diagnosing DTC B3031.

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?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Install a scan tool.
  2. Momentarily rotate the ignition switch to CRANK (do not start the vehicle).
  3. Release the ignition switch to ON.
  4. Select the body control module display DTCs function on the scan tool.

Does the scan tool display DTC B3031 as a current DTC?

Go to Step 3

Go to Step 4

3

Does the scan tool display DTC B2947, B2948, B2957, B2958, B2960 or B3033?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

--

4
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition.
  3. Start the vehicle.
  4. Select the body control module display DTCs function on the scan tool.

Does the DTC reset?

Go to Step 3

System OK