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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1431 (RETAINED ACCESSORY POWER SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDIAGNOSTIC SYSTEM CHECK - RETAINED ACCESSORY POWERTEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Test Description

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. 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. 2:  Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
  2. 3:  This step tests for valid system power moding in all ignition switch positions.
  3. 5:  The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
Diagnostic System Check - Retained Accessory Power

Step Action Yes No
Schematic Reference: Data Link Connector (DLC) Schematics in Data Link Communications
1 Install a scan tool.
Does the scan tool power up?		 Go to Step 2  Go to Scan Tool Does Not Power Up in Data Link Communications
2 
  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the body control module (BCM).
Does the scan tool communicate with the BCM?		 Go to Step 3  Go to Scan Tool Does Not Communicate with Class 2 Device (W/O Immobilizer)Scan Tool Does Not Communicate with Class 2 Device (W/ Immobilizer) in Data Link Communications
3 
IMPORTANT: Open the driver door and leave it open during this test. This will disable the retained accessory power (RAP) mode and eliminate this power mode from the power mode parameter list.
RENDER: 1.0x

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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.