GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Blazer - 4WD - RHD 🢒 Body and Accessories 🢒 Data Link Communications 🢒 DTC B2958 Security System Sensor Data Circuit High

Object Number: 573177 Size: LF
Theft Deterrent System Components
Theft Deterrent System Schematics
Theft Deterrent System Schematic Icons

Circuit Description

The body control module (BCM) will read an analog voltage form the Passlock™ sensor. Based on an internal reference, the BCM will determine if the measured voltage is in 1 of the following conditions:

    • Open
    • Shorted to ground
    • A valid code
    • A tamper code

There are 10 possible valid code combination. The BCM will only recognize the last learned valid code.

Conditions for Setting the DTC
    • The ignition switch is ON.
    • The 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
    • When replacing the Passlock™ sensor, all of the following components are included as a replacement part and must be replaced:
       - The lock
       - The sensor
       - The filter
       - The harness
    • Use a scan tool in order to inspect the Passlock™ data voltage and the Passlock™ code.
    • Perform a visual inspection of the wiring and the connectors.
    • You may be directed to this table from the VTD Systems Check without a DTC B2958 being set. If you were directed to this table, follow all of the steps in this diagnostic.
    • When directed to this table, DTC B2958 may have a history status.
    • When connecting connector C211, make measurements on the harness side of the connector.

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.

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

    3.

  3. Tests for high resistance or an open in the 12v reference circuit.

    4.

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

    5.

  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

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect 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 greater than the specified value?

4.9 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?

0.4 v

Go to Step 5

Go to Step 7

5

  1. Disconnect the fused jumper wire.
  2. Measure the voltage between the 12v reference circuit of the Passlock™ sensor and the ground circuit of the Passlock™ sensor.

Does the voltage measure less than the specified value?

12.0 v

Go to Step 6

Go to Step 11

6

Test the 12v 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 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: Perform the set up procedure for the body control module .

Replace the body control module. 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 in the lock cylinder housing assembly.

  1. To disassemble, refer to Lock Housing Assembly - Disassemble - Off Vehicle .
  2. To assemble, refer to Lock Housing Assembly - Assemble - Off Vehicle .

Did you complete the replacement?

--

Go to Step 13

--

13

Perform one of the following Passlock™ learn procedures:

    •  PASSLOCK Reprogramming Seed and Key (10 minutes)
    •  PASSLOCK Reprogramming Auto Learn (30 minutes)

Is the repair complete?

--

Go to Step 14

--

14
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition
  3. Momentarily rotate the ignition switch to CRANK (do not start the vehicle).
  4. Release the ignition switch to ON.
  5. 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