GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Malibu 🢒 Body and Accessories 🢒 Body Control System 🢒 DTC B3031 Key Decoder Device in Assem Learn Mode

Object Number: 281486 Size: MF
Theft Deterrent System Components
Cell 133: Fuel Tank Module, Instrument Cluster and Passlock Cylinder
Handling ESD Sensitive Parts Notice

Circuit Description

This DTC is set when the body control module (BCM) is in the learn mode. The Scan Tool shows the Passlock™ signal toggle under the following conditions:

    • When the BCM is in the learn mode
    • The ignition switch is cycled

Conditions for Setting the DTC

All of the following conditions must be met:

    • The Passlock™ option is enabled.
    • Ignition 0 is inactive.
    • The Passlock™ key code has not been learned.

Action Taken When the DTC Sets
    • The BCM stores the DTC B3031 in the BCM memory.
    • The vehicle will not start.

Conditions for Clearing the DTC
    • The BCM goes to sleep and reinitializes with the fault cleared.
    • All of the BCM history codes will be cleared after 100 ignition cycles (from OFF to RUN) with no current codes active during the 100 ignition cycles.
    • A Scan Tool is used.

Diagnostic Aids
    • If a new BCM or ignition switch has been installed in the vehicle, this DTC will set.
    • When the diagnostics direct you to take the electrical measurements at the wiring harness junction blocks, refer to Power Distribution Schematics for terminal assignments of the wiring harness junction blocks.
    • If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while wiggling the wiring and connectors. This action often causes the malfunction to appear.

Test Description

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

  1. This step determines if the Scan Tool is reading that the BCM is sending the proper voltage.

    2.

  2. This step determines if the BCM is actually sending the proper voltage.

    3.

  3. This step determines if a short to ground exists between the BCM and the Passlock® sensor.

    4.

  4. This step determines if an open in CKT 1459 exists between the BCM and the Passlock® sensor.

    5.

  5. This step determines if a short to ground or open exists within the Passlock® sensor.

    6.

  6. This step determines if a short to the battery exists in CKT 1835 between the BCM and the Passlock® sensor.

    7.

  7. This step determines if a short to ground exists in CKT 1835 between the BCM and the Passlock® sensor.

    8.

  8. This step determines if an open exists in CKT 1835 between the BCM and the Passlock® sensor.

    9.

  9. This step determines if the proper voltage exists between terminal A and terminal B of the Passlock® sensor.

    10.

  10. This step determines if an open exists in CKT 1836 between the BCM and the Passlock® sensor.

Step

Action

Value(s)

Yes

No

Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.

1

Was the Theft Deterrent Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2

  1. Use the Scan Tool in the BCM SECURITY DATA menu.
  2. Turn the ignition switch to the CRANK position.

Is the Passlock® DATA VOLTAGE reading within the specified range?

5 V

Go to Step 3

Go to Step 29

3

Inspect for a poor connection at the Passlock® sensor connector.

Was a poor connection found?

--

Go to Step 4

Go to Step 5

4

Repair the poor connection. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 29

--

5

  1. Turn the ignition switch to the ON position.
  2. Use the J 39200 in order to backprobe and measure the voltage in CKT 1459 between the Passlock® sensor connector terminal C and ground.

Is the measured resistance within the specified range?

B+

Go to Step 13

Go to Step 6

6

  1. Disconnect the Passlock® sensor.
  2. Disconnect the BCM connector C3.
  3. Use the J 39200 in order to measure the resistance in CKT 1459 between the Passlock® sensor connector terminal C and ground.

Is the measured resistance within the specified range?

∞

Go to Step 8

Go to Step 7

7

Repair the short to ground in CKT 1459 between the Passlock® sensor connector terminal C and the BCM connector C3 terminal B4. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 29

--

8

Use the J 39200 in order to measure the resistance in CKT 1459 between the Passlock® sensor connector terminal C and the BCM connector C3 terminal B4.

Is the measured resistance within the specified range?

0 ohms

Go to Step 10

Go to Step 9

9

Repair the open in CKT 1459 between the Passlock® sensor connector terminal C and the BCM connector C3 terminal B4. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 29

--

10

  1. Reconnect the BCM connector C3.
  2. Turn the ignition switch to the RUN position.
  3. Use the J 39200 in order to backprobe CKT 1459 and read the voltage between the BCM connector C3 terminal B4 and ground.

Is the measured voltage within the specified range?

B+

Go to Step 11

Go to Step 28

11

Inspect for a poor connection at the BCM connector C3.

Was a poor connection found?

--

Go to Step 12

Go to Step 28

12

Repair the poor connection at the BCM connector C3. Refer to Wiring Repairs in Wiring Systems

Is the repair complete?

--

Go to Step 29

--

13
  1. Reconnect all of the disconnected components.
  2. Turn the ignition switch to the RUN position.
  3. Use the J 39200 in order to backprobe and measure the voltage between cavity B and cavity C of the Passlock® sensor connector.

Is the measured voltage within the specified range?

B+

Go to Step 22

Go to Step 14

14

  1. Disconnect the Passlock® sensor.
  2. Disconnect the BCM connector C2.
  3. Use the J 39200 in order to measure the voltage in CKT 1835 between the Passlock® sensor connector terminal B and ground.

Is the measured voltage within the specified range?

0 V

Go to Step 16

Go to Step 15

15

Repair the short to B+ in CKT 1835 between the Passlock® sensor connector terminal C and the BCM connector C2 terminal A6.

Is the repair complete?

--

Go to Step 29

--

16

  1. Disconnect the Passlock® sensor.
  2. Disconnect the BCM connector C2.
  3. Use the J 39200 in order to measure the resistance in CKT 1835 between the Passlock® sensor connector terminal B and ground.

Is the measured resistance within the specified range?

∞

Go to Step 18

Go to Step 17

17

Repair the short to ground in CKT 1835 between the Passlock® sensor connector terminal B and the BCM connector C2 terminal A6.

Is the repair complete?

--

Go to Step 29

--

18

Use the J 39200 in order to measure the resistance in CKT 1835 between the Passlock® sensor connector terminal B and the BCM connector C2 terminal A6.

Is the measured resistance within the specified range?

0 ohms

Go to Step 20

Go to Step 19

19

Repair the open in CKT 1835 between the Passlock® sensor connector terminal C and the BCM connector C2 terminal A6.

Is the repair complete?

--

Go to Step 29

--

20

Inspect for a poor connection at the BCM connector C2 terminal A6.

Was a poor connection found?

--

Go to Step 21

Go to Step 28

21

Repair the poor connection at the BCM connector C2 terminal A6. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 29

--

22

  1. Reconnect all of the disconnected components.
  2. Turn the ignition switch to the RUN position.
  3. Use the J 39200 in order to backprobe and measure the voltage between terminal A and terminal B of the Passlock® sensor connector.

Is the measured voltage within the specified range?

5 V

Go to Step 27

Go to Step 23

23

  1. Disconnect the Passlock® sensor.
  2. Disconnect the BCM connector C2.
  3. Use the J 39200 in order to measure the resistance in CKT 1836 between the Passlock® sensor connector terminal A and the BCM connector C2 terminal B6.

Is the measured resistance within the specified range?

0 ohms

Go to Step 25

Go to Step 24

24

Repair the open in CKT 1836 between the Passlock® sensor connector terminal A and the BCM connector C2 terminal B6.

Is the repair complete?

--

Go to Step 29

--

25

Inspect for a poor connection at the BCM connector C2 terminal B6.

Was a poor connection found?

--

Go to Step 26

Go to Step 28

26

Repair the poor connection at the BCM connector C2 terminal B6. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 29

--

27

Replace the Passlock® sensor.

Is the repair complete?

--

Go to Step 29

--

28

Replace the BCM. Refer to the following procedures:

    •  Body Control Module (BCM) Programming/RPO Configuration in Body Control Systems
    •  Body Control Module Replacement in Body Control Systems

Is the repair complete?

--

Go to Step 29

--

29

Clear the DTCs from the memory.

Are the DTCs cleared from the memory?

--

Go to Diagnostic System Check - Theft Deterrent

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