GM Service Manual Online
For 1990-2009 cars only

Object Number: 900023  Size: MF

Circuit Description

The Passlock™ system is provided in order to prevent vehicle theft if the ignition lock cylinder is forced to rotate. The Passlock™ controller reads the coded Passlock™ data signal. The data consists of a voltage generated by a voltage divider network created between the Passlock™ assembly and the Passlock™ controller. If the data is correct , indicating rotation of the lock cylinder with the proper mechanically cut key, then the Passlock™ controller sends a password to the Powertrain controller over the class 2 bus to indicate that starter engagement should be allowed. The Passlock™ controller also interfaces with the driver displays subsystem to indicate, via a Security telltale, the Passlock™ subsystem's status and acute subsystem failures.

Conditions for Setting the DTC

    • The ignition switch is ON.
    • The body control module (BCM) signal input is greater than 4.9 volts for 1 second after turning the ignition switch to the CRANK position.

Action Taken When the DTC Sets

    • The DTC will set only when the engine is running
    • The BCM will be in the fail enable mode allowing the vehicle to start and run.
    • The security indicator will be ON.

Conditions for Clearing the DTC

    • The current DTC will clear once an ignition cycle has occurred without the fault recurring.
    • After 100 concurrent ignition cycles occur without the fault recurring, a history DTC clears.
    • Using a scan tool.

Diagnostic Aids

    • Use a scan tool in order to inspect the Passlock™ data voltage and the Passlock™ code.
    • Inspect the Passlock™ sensor harness for an intermittent or a short to battery. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • You may be directed to this table from the VTD Diagnostic System Check without a DTC B2958 being set. If you were directed to this table, follow all of the steps in this diagnostic table.
    • When directed to this table, DTC B2958 may have a history status.

Test Description

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

  1. Tests for proper operation of the circuit in the high voltage range.

  2. Tests for proper operation of the circuit in the low voltage range.

  3. Tests for high resistance or an open in the 5-volt reference circuit.

  4. Tests for a short to voltage, a high resistance, or an open in the signal circuit.

  5. Tests for high resistance or an open in the ground circuit.

Step

Action

Value(s)

Yes

No

1

Did you perform the Theft Deterrent (VTD) Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

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. With a scan tool, observe the Passlock™ Data Voltage in the Body Control Module Security Data list.

Does the scan tool indicate that the Passlock™ Data Voltage is within the specified range?

0.4-4.9 V

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the ignition switch connector.
  3. Back the off/run/crank voltage terminal and the 5-volt reference terminal for the ignition switch harness connector.
  4. Reconnect the ignition switch harness connector.
  5. Turn ON the ignition, with the engine OFF.
  6. With a scan tool observe the Passlock™ Data Voltage in the Body Control Module Security Data list.

Does the scan tool indicate that the Passlock™ Data Voltage is greater than the specified value?

4.53 V

Go to Step 4

Go to Step 9

4

  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the signal circuit of the Passlock™ sensor and the ground circuit of the Passlock™ sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool observe the Passlock™ Data Voltage in the Body Control Module Security Data list.

Does the scan tool indicate that the Passlock™ Data Voltage is less than the specified value?

1.6 V

Go to Step 5

Go to Step 7

5

  1. Disconnect the fused jumper wire.
  2. Measure the voltage between the 5-volt reference circuit of the Passlock™ sensor and the ground circuit of the Passlock™ sensor.

Does the voltage measure less than the specified value?

4.53 V

Go to Step 6

Go to Step 11

6

Test the 5-volt reference circuit of the Passlock™ sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 9

7

Test the signal circuit of the Passlock™ sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 8

8

Test the ground circuit of the Passlock™ sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 9

9

Inspect for poor connections at the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 10

10

Important: When replacing the BCM. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

--

Go to Step 14

--

11

Inspect for poor connections at the Passlock™ sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 12

12

Replace the Passlock™ sensor. Refer to Ignition and Start Switch Replacement in Steering Wheel and Column.

Did you complete the replacement?

--

Go to Step 13

--

13

Perform the Programming Theft Deterrent System Components procedure.

Is the repair complete?

--

Go to Step 14

--

14

  1. Resecure the off/run/crank voltage and 5-volt reference circuit terminals back into the ignition switch connector.
  2. Use the scan tool in order to clear the DTCs.
  3. Turn OFF the ignition
  4. Momentarily rotate the ignition switch to CRANK. Do not start the vehicle.
  5. Release the ignition switch to ON.
  6. Select the body control module display DTCs function on the scan tool.

Does the DTC reset?

--

Go to Step 3

Go to Step 15

15

Attempt to start the vehicle.

Does the engine start and run?

--

System OK

Go to Step 3