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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1799 (IMMOBILIZER SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B2957TEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Test Description

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 3:  Tests for proper operation of the circuit in the high voltage range.
  2. 4:  Tests for a short to ground in the Passlock™ Security System Sensor Signal circuit.
DTC B2957

Step Action Values Yes No
Schematic Reference: Theft Deterrent System Schematics
Connector End View Reference: Vehicle Access Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
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 (BCM) 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 connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Passlock™ data voltage in the BCM 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 7  Go to Step 4 
4  Test the Passlock™ security system sensor signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .
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 .
Did you find and correct the condition?		 - Go to Step 10  Go to Step 6 
6 Replace the BCM. Refer to Control Module References for replacement, setup and programming.
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 .
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. Refer to Ignition Lock Cylinder Case Replacement .
Did you complete the replacement?		 - Go to Step 9  -
9 Perform the Programming Immobilizer System Components  procedure.
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
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.