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 117 (ENGINE CONTROLS - SELF-DIAGNOSTICS)DIAGNOSTIC TESTSDTC P0201-P0204: INJECTOR CONTROL CIRCUITDIAGNOSTIC PROCEDURES
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Diagnostic Procedures
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Saturn LW200, 2002 Saturn L200, and 2002 Saturn L100. However, it is still accessible from the selected car via links, so may be relevant.
- Turn ignition off for 10 seconds. Start engine and operate engine for one minute. Using scan tool, monitor status of DTC. If this DTC failed this ignition cycle, go to next step. If this DTC did not fail this ignition cycle, problem is intermittent. See DIAGNOSTIC AIDS .
- Turn ignition off. Disconnect affected fuel injector harness connector. Connect Injector Test Light (J-34730-405) to injector harness connector. Start or crank engine. If injector test light is always off, go to next step. If injector test light pulses, check for loose connection at injector connector. Repair as necessary. If connector is okay, replace fuel injector. If injector test light is always on, check affected control circuit for short to ground between fuel injector and PCM. Repair as necessary. If circuit is okay, replace PCM.
- Turn ignition on, with engine off. Connect a test light between ground and fuel injector harness connector terminal "A" (Pink wire). If test light illuminates, go to next step. If test light does not illuminate, repair open in Pink wire. See WIRING DIAGRAMS article.
- Using a DVOM, check voltage on affected fuel injector harness connector terminal "B". If voltage is more than 0.2 volt, repair short to voltage in circuit. If voltage is not more than 0.2 volt, check for open in circuit or loose connection. Repair as necessary. If circuit or terminals are okay, replace PCM.
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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.