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 143 (ENGINE CONTROLS - SYSTEM & COMPONENT TESTING)FUEL SYSTEM (BI-FUEL & CNG)FUEL INJECTOR BALANCE TEST WITH TECH 2DIAGNOSTIC PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Diagnostic Procedure
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedure
WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2002 Saturn Vue, 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, and 2002 Oldsmobile Bravada. However, it is still accessible from the selected car via links, so may be relevant.
- Perform Alternative Fuels Diagnostic System Check - Engine Controls. See ALTERNATIVE FUELS DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing Alternative Fuels Diagnostic System Check - Engine Controls, go to next step.
- Did you perform Fuel Injector Coil Test? If yes, go to next step. If no, go to FUEL INJECTOR COIL TEST (BI-FUEL & CNG) .
- Start and idle engine. Observe Fuel Rail Pressure (FRP) sensor parameter with scan tool. Is fuel pressure within 40-50 psi (275-345 kPa)? If yes, go to next step. If no, go to FUEL SYSTEM DIAGNOSIS (BI-FUEL & CNG) .
- Turn OFF the ignition. Turn ON the ignition, with the engine OFF. Monitor Fuel Rail Pressure (FRP) sensor parameter with scan tool. Does fuel rail pressure remain constant? If yes, go to next step. If no, go to FUEL SYSTEM DIAGNOSIS (BI-FUEL & CNG) .
CAUTION:
DO NOT repeat any portion of this test before running engine in order to prevent engine from flooding.
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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.