Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 18 (BODY CONTROL MODULES)SELF-DIAGNOSTIC SYSTEMINSTRUMENT PANEL CLUSTER DIAGNOSTIC SYSTEM CHECK
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Instrument Panel Cluster Diagnostic System Check
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Instrument Panel Cluster Diagnostic System Check
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2002 GMC Savana, 2002 Chevrolet Chevy Express, 2001 GMC Savana Special, 2001 GMC Savana Camper Special, and 2001 GMC Savana. However, it is still accessible from the selected car via links, so may be relevant.
- Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC), located below steering column. Turn ignition switch to RUN position. If scan tool powers up, go to next step. If scan tool does not power up, go to TEST A: SCAN TOOL DOES NOT POWER UP under SYSTEM TESTS.
- Using scan tool, attempt to establish communications with Powertrain Control Module (PCM) and Sensing and Diagnostic Module (SDM). If scan tool communicates with both modules, go to next step. If scan tool does not communicate with both modules, go to TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS.
- Attempt to communicate with 4-WAL 3 sensor (EBCM). If scan tool communicates with EBCM, go to next step. If scan tool does not communicate with EBCM, go to TEST C: SCAN TOOL DOES NOT COMMUNICATE WITH EBCM under SYSTEM TESTS.
- Select DISPLAY DTCs function for 4-WAL 3 Sensor (EBCM), Powertrain Control Module (PCM) and Supplemental Inflatable Restraint (SDM) module. If scan tool displays any DTCs, go to next step. If scan tool does not display DTCs, repair by symptom. See INSTRUMENT PANELS - CHEVY EXPRESS & SAVANA article.
- If scan tool displays DTCs which begin with "U", go to TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE and TEST C: SCAN TOOL DOES NOT COMMUNICATE WITH EBCM under SYSTEM TESTS. If scan tool does not display DTCs which begin with "U", go to next step.
- If scan tool does not display DTCs B1000, B1004 or B1009, go to next step. If scan tool displays DTCs B1000, B1004 or B1009, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
- If scan tool displays DTC P0562, P0563, P1637 or P1638, go to ENGINE ELECTRICAL SYSTEM DIAGNOSTIC SYSTEM CHECK . If other DTCs are displayed, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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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.