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 1746 (LIGHTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P1574 (PCMW/L66)CIRCUIT/SYSTEM TESTING
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Circuit/System Testing
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
- Perform the stoplamp switch adjustment, refer to Stop Lamp Switch Adjustment , clear all DTCs, and operate the vehicle within the Conditions for Running the DTC.
- If DTC P1574 resets as current, test the stop lamp switch signal circuit for a short to ground, short to voltage, or open.
- If circuits test OK, replace the 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.