Circuit/System Testing

2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 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 CKP sensor.
  2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal 2 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 ECM.
  3. Ignition ON, engine OFF, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  4. Ignition ON, engine OFF, test for 4.8-5.2 volts between the signal circuit terminal 3 and ground.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  5. Ignition OFF, connect a fused jumper wire to signal circuit terminal 3.
  6. Ignition ON, momentarily touch the other end of the fused jumper wire to the battery negative post repeatedly. The CKP Active Counter should increment.
    • If the CKP Active Counter increments, test or replace the CKP sensor.
    • If the CKP Active Counter does not increment, replace the ECM.
  7. Ignition OFF, inspect the CKP sensor for correct installation.
    • If the CKP sensor is loose, inspect the sensor and the O-ring for damage. Replace as necessary.
  8. Inspect the engine for the following conditions:
    • Engine oil for debris
    • Crankshaft reluctor wheel for damage
    • Timing chain, tensioner, and sprockets for wear or damage
    • If debris is found in the engine oil, inspect the internal engine components to determine the cause. Repair or replace any worn or damaged components.
  9. If all circuits and components test normal, test or replace the CKP 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.