GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 GMC K Sierra - 4WD 🢒 Body and Accessories 🢒 Theft Deterrent 🢒 DTC B2947 Security System Sensor Power CKT Low

Object Number: 573265 Size: LF
Theft Deterrent System Components
Theft Deterrent System Schematics
Theft Deterrent System Schematic Icons

Circuit Description

The body control module (BCM) supplies power to the Passlock™ sensor on the Security Sensor Power line (12v Reference).

When the Passlock™ sensor is powered and the ignition switch is rotated to the CRANK position, the hall effect security sensor will latch and provide a code to the BCM. The BCM will then compare this code to the code in the previous ignition cycle. If the latched value is the same as the last ignition cycle value, the test has passed. When the ignition switch is switched to the OFF position, the sensor is no longer powered and resets the sensor latch circuit.

In the next ignition cycle, the Passlock™ sensor waits for an ignition switch crank input and verifies the sensor code and compares the sensor code to the last stored valid code.

Conditions for Setting the DTC
    • The ignition switch is in the ON position.
    • The BCM is unable to produce the 9-16 volts required for the Passlock™ sensor operation. This may be due to a module, a wiring, or a sensor problem.

Action Taken When the DTC Sets
    • The vehicle does not start if the fault occurs before you start the vehicle. The security telltale will be ON.
    • If the vehicle is running when the fault occurs, the BCM will be in the fail enable mode allowing the vehicle to start and to run. The security telltale will be ON.

Conditions for Clearing the MIL/DTC
    • The DTC will clear after an ignition cycle occurs without the fault recurring.
    • The BCM history code clears after 100 concurrent ignition cycles occur without the fault recurring.
    • 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.
    • Inspect the Passlock™ sensor harness for an intermittent or a short to ground. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. Verifies the existence of this current DTC.

    2.

  2. Tests for a short to ground in the Passlock™ sensor or the pigtail harness.

    3.

  3. Tests for a short to ground in the 12v reference 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. Turn ON the ignition, with the engine OFF.
  3. Select the body control module display DTCs function on the scan tool.

Does the scan tool display DTC B2947 as a current DTC?

--

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

  1. Disconnect the Passlock™ sensor connector.
  2. Measure the voltage from the 12v reference circuit to a good ground.

Does the voltage measure within the specified range?

B+

Go to Step 7

Go to Step 4

4

Test the 12v reference circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 5

5

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 10

Go to Step 6

6

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 Systems.

Did you complete the replacement?

--

Go to Step 10

--

7

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 10

Go to Step 8

8

Replace the Passlock™ sensor in the electronic column lock module assembly. Use the appropriate procedure from the following list:

    • Tilt Wheel
       - With column shift
             1. Disassemble Electronic Column Lock Module - Disassemble - Off Vehicle
             2. Assemble Electronic Column Lock Module - Assemble - Off Vehicle
       - With floor shift
             1. Disassemble Electronic Column Lock Module - Disassemble - Off Vehicle
             2. Assemble Electronic Column Lock Module - Assemble - Off Vehicle
       - Export
             1. Disassemble Electronic Column Lock Module - Disassemble - Off Vehicle
             2. Assemble Electronic Column Lock Module - Assemble - Off Vehicle
    • Standard Wheel
       - With column shift export
             1. Disassemble Electronic Column Lock Module - Disassemble - Off Vehicle
             2. Assemble Electronic Column Lock Module - Assemble - Off Vehicle
       - With floor shift export
             1. Disassemble Electronic Column Lock Module - Disassemble - Off Vehicle
             2. Assemble Electronic Column Lock Module - Assemble - Off Vehicle

Did you complete the replacement?

--

Go to Step 9

--

9

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 10

--

10
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition
  3. Turn ON the ignition, with the engine OFF.
  4. Select the body control module display DTCs function on the scan tool.

Does the DTC reset?

--

Go to Step 3

System OK