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 15 (BODY CONTROL MODULES)SELF-DIAGNOSTIC SYSTEMRETAINED ACCESSORY POWER SYSTEM DIAGNOSTIC SYSTEM CHECK
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Retained Accessory Power System Diagnostic System Check
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Retained Accessory Power System Diagnostic System Check
WARNING: This page is about a different car, the 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, 2001 Chevrolet Monte Carlo, and 2001 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Use this check as starting point for any retained accessory power system complaint.
- Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). 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 D: SCAN TOOL DOES NOT POWER UP under SYSTEM TESTS.
- Turn ignition switch to RUN position. Using scan tool, attempt to establish communication with Body Control Module (BCM). If scan tool communicates with BCM, go to next step. If scan tool does not communicate with BCM, go to TEST C: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS.
- Select DISPLAY DTCs function for BCM. If any DTCs are present, go to next step. If no DTCs are present, go to appropriate symptom test. See SYSTEM TESTS .
- If DTCs U1000-U1305 are not present, go to next step. If DTCs U1000-U1305 are present, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . Repair as necessary.
- Check for DTCs B1000, B1339 or B1349. If DTCs are not present, go to next step. If any DTC is present, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . Repair as necessary.
- Check for DTCs B1477 or B1478. If DTCs are not present, go to appropriate symptom test. See SYSTEM TESTS . If any DTC is present, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . Repair as necessary.
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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.