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 (DIESEL)WATER-IN-FUEL LIGHT ALWAYS ON (6.5L)DIAGNOSTIC 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 Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 6.5L CAB & CHASSIS, CHEVY EXPRESS & SAVANA article. After performing Diagnostic System Check - Engine Controls, go to next step.
- Turn ON the ignition, with the engine OFF. Does water-in-fuel light illuminate briefly, then go out? If yes, go to step 4. If no, go to next step.
- Does water-in-fuel light stay ON? If yes, go to step 5. If no, go to.WATER-IN-FUEL LIGHT INOPERATIVE (6.5L)
- Operate vehicle under conditions which problem was noted. Does system operate normally? If yes, system is okay. If no, go to step 2.
- Disconnect water-in-fuel sensor harness connector. Turn ON the ignition, with the engine OFF. Probe Water-In-Fuel Indicator Control circuit at harness connector with Test Light (J 34142-B) connected to battery voltage. Does test light illuminate? If yes, go to next step. If no, go to step 7.
- Repair short to ground in Water-In-Fuel Indicator Control circuit. After repairs, go to step 8.
- Replace water-in-fuel sensor. After repairs, go to next step.
- Start engine. Operate vehicle within conditions under which problem was noted. Does system operate normally? If yes, system is okay. If no, go to step 2.
NOTE:
Before proceeding with this step, drain any water from fuel system.
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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.