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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Sonoma Pickup - 4WD 🢒 Body and Accessories 🢒 Theft Deterrent 🢒 DTC B2948 Security System Sensor Power CKT 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) supplies power to the Passlock sensor on CKT 812.

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 OFF position.
    • The BCM turns the sensor power OFF for approximately 0.1 seconds when the ignition switch is turned OFF.
    • During the 0.1 second shut down of voltage, if the BCM senses battery voltage the DTC will set.
    • The sensor power will turn OFF after the 20 minute BCM shut down period.

Action Taken When the DTC Sets

The vehicle will continue to start and run with the security indicator ON.

Conditions for Clearing the DTC
    • The DTC clears once an ignition cycle occurs without the fault recurring.
    • The BCM history codes will clear after 100 concurrent ignition cycles occur without the fault recurring.
    • Use a scan tool in order to clear history and current DTCs.

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.

Test Description

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

  1. Tests for the proper operation of the circuit in the low voltage range. If the voltage does not drop during ignition OFF, the 12v reference circuit is shorted to voltage.

    2.

  2. Tests for a short to voltage 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 B2948 as a current DTC?

--

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

Important: The use of DMM J39200 is crucial in this step because voltage may be interrupted for 10 milliseconds only.

  1. Disconnect the Passlock™ sensor connector.
  2. Connect a J 39200 between the 12v reference circuit and ground.
  3. Set the "MIN MAX" mode to the 1 millisecond peak and start to record.
  4. Turn OFF the ignition.
  5. Stop the recording and review the recorded "MIN" value.

Does the voltage measure near the specified value?

0v

Go to Step 7

Go to Step 4

4

Test the 12v reference circuit for a short to voltage. 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
    • Standard 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

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

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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