GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Jimmy - 4WD 🢒 DTC 🢒 DTC B2948 Security System Sensor Power CKT High

Object Number: 381577 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.
    • Inspect the Passlock sensor harness for an intermittent or a short to battery. Refer to Intermittents and Poor Connections in Wiring Systems.

Test Description

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

  1. This step isolates the short to battery between the BCM and the harness.

    2.

  2. This step isolates the short to battery between the Passlock sensor and the harness.

Step

Action

Value(s)

Yes

No

1

Did you perform the VTD Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the BCM connector C1.
  3. Use a J 39200 digital multimeter (DMM) in order to measure the voltage from the BCM connector C1 terminal B3 and ground.

Is the voltage within the specified value?

9-16 V

Go to Step 3

Go to Step 6

3

  1. Disconnect connector C211 at the base of the steering column.
  2. Use a J 39200 DMM in order to measure the resistance from connector C1 terminal B3 to terminal A2.

Does the J 39200 DMM indicate the specified value?

(OL) Infinite

Go to Step 5

Go to Step 4

4

Locate and repair the short to battery in CKT 812.

Is the repair complete?

--

Go to Step 7

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5
  1. Replace the Passlock sensor.
    2. • To disassemble Lock Housing:
    • To reassemble Lock Housing:
  2. Follow the Passlock learn procedure. Refer to PASSLOCK Reprogramming Seed and Key or PASSLOCK Reprogramming Auto Learn .

Is the repair complete?

--

Go to Step 7

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6

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

Is the repair complete?

--

Go to Step 7

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7
  1. Reconnect all of the previously disconnected connectors and the components.
  2. Turn the ignition switch to the ON position.
  3. Connect the scan tool.
  4. Clear the DTCs.
  5. Perform one of the following Relearn Procedures if the Passlock sensor or the BCM have been replaced:
    6. • Seed and Key in 10 minutes PASSLOCK Reprogramming Seed and Key
    • Auto Learn in 30 minutes PASSLOCK Reprogramming Auto Learn

Is the operation complete?

--

Go to Diagnostic System Check - Theft Deterrent

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