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 SYSTEMCRUISE CONTROL SYSTEM DIAGNOSTIC SYSTEM CHECK2002
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Cruise Control System Diagnostic System Check: 2002
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION 2002
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 communicate with Powertrain Control Module (PCM). If scan tool communicates with PCM, go to next step. If scan tool does not communicate with PCM, go to TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS.
- Using scan tool, 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 ELECTRONIC BRAKE CONTROL MODULE under SYSTEM TESTS.
- Select DISPLAY DTCs function on scan tool for PCM and EBCM. If scan tool displays any DTCs for the modules listed above, go to next step. If scan tool does not display any DTCs for the modules listed above, go to CRUISE CONTROL SYMPTOMS - CHEVY EXPRESS & SAVANA article.
- If scan tool displays any DTCs that begin with a "U", go to TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE and TEST C: SCAN TOOL DOES NOT COMMUNICATE WITH ELECTRONIC BRAKE CONTROL MODULE under SYSTEM TESTS. If scan tool does not display any DTCs that begin with a "U", go to next step.
- If scan tool displays DTC P0562, P0563, P1637, or P1638, go to 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.