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.
Diagnostic Procedures
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
- Did you perform the Inspection/Maintenance (I/M) system check? If yes, go to next step. If no, see INSPECTION/MAINTENANCE SYSTEM CHECK .
- Ensure that the vehicle is within the Conditions for Running. See CONDITIONS FOR RUNNING . Turn OFF all accessories, e.g., A/C, blower fan, etc. Set vehicle parking brake. Verify transmission is in Park (A/T) or Neutral (M/T). Start engine and allow engine to idle. Idle engine until an operating temperature of at least 158°F (70°C) is reached. This may be up to 8-10 minutes depending on the start up coolant temperature. Once the engine is started, DO NOT turn OFF the engine for the remainder of the procedure until the test is complete. When complete, go to next step.
- For the next group of tests to run, vehicle must operate in the following conditions:
- Acceleration at part throttle to 45-55 MPH (56-90 km/h).
- Speed maintained for 4 minutes or until I/M System Status indicator updates to YES.
- Important: For this test to run, the vehicle must operate in the following conditions:
- Deceleration to zero MPH.
- Engine idling for 2 minutes while service brake depressed, automatic transmission in Drive and manual transmission in Neutral with clutch pedal depressed.
- For the next group of tests to run, vehicle must operate in the following conditions:
- Acceleration at part throttle to 45-55 MPH (56-90 km/h).
- Speed maintained for 4 minutes or until I/M System Status indicator updates to YES.
- With a scan tool, observe I/M SYSTEM STATUS display. Did all of I/M system status indicators update to YES? If yes, go to next step. If no, go to I/M SYSTEM SET procedure for the indicated systems.
- Using scan tool, observe emission related DTC portion of I/M SYSTEM STATUS display. Does the scan tool indicate any emission related DTCs set? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
WARNING:
Road test 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.
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.
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.