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 DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROL SYSTEM - SELF-DIAGNOSTICS - 4.2LDRIVE CYCLESINSPECTION/MAINTENANCE EVAPORATIVE EMISSION SYSTEM SET PROCEDUREDIAGNOSTIC PROCEDURES
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Diagnostic Procedures
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedures
- Did you perform the Inspection/Maintenance (I/M) System Check? If yes, go to next step. If no, see INSPECTION/MAINTENANCE SYSTEM CHECK .
- Using scan tool, select Special Functions. Determine if the vehicle is equipped with a Service Bay Test for the EVAP System. Is the vehicle equipped with EVAP Service Bay Test? If yes, go to next step. If no, go to step 5.
- Ensure that the vehicle is within the CONDITIONS FOR RUNNING . Turn OFF all of the accessories (e.g., A/C, blower fan, etc.). Following the directions on scan tool, perform the EVAP Service Bay Test. Did the EVAP System pass the Service Bay Test? If yes, go to step 8. If no, go to next step.
- Observe scan tool Service Bay Test for an indication of why the test did not pass, (e.g., failed DTC, test aborted, etc.). Repair condition as necessary. After repair, see INSPECTION/MAINTENANCE COMPLETE SYSTEM SET PROCEDURE .
WARNING:
Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.
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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.