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 1811 (ENGINE COOLING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESLOW ENGINE COOLANT INDICATOR ALWAYS ONCIRCUIT/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.
IMPORTANT:
Circuit/System Verification must be performed before performing the Circuit/System Testing.
- Turn ON the ignition, with the engine OFF.
- Verify that the low coolant indicator turns ON and OFF with each command when the instrument cluster indicators are commanded ON and OFF with a scan tool.
- If the low coolant level indicator does NOT turn OFF, test for poor connections at the IPC or a faulty IPC.
- Ignition ON, disconnect the coolant level switch.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal A and ground.
- If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test the circuit for a short to ground.
- Ignition ON, use a 3A fused jumper wire to connect harness terminal A to terminal B.
- If the low coolant level indicator turns OFF, replace the coolant level switch.
- If the low coolant level indicator does not turn OFF, test the signal circuit of the coolant switch for an open circuit or high resistance.
- If the signal circuit test normal, inspect for poor connections at the BCM or a faulty BCM.
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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.