Circuit/System Testing

2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the B34 ECT sensor.
  2. Inspect the ECT sensor terminals for corrosion and for engine coolant leaking through the sensor.
  3. Ignition OFF for 90 seconds, test for less than 5 ohms between the low reference circuit terminal A and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  4. Ignition ON, verify the scan tool ECT Sensor parameter is colder than -39Β°C (-38Β°F).
    • If warmer than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the K20 ECM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT Sensor parameter is warmer than 142Β°C (288Β°F).
    • If colder than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  6. If the circuits test normal, test or replace the B34 ECT sensor.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.