Circuit/System Testing

2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
  1. Inspect for any contamination, water intrusion or debris on the sensing elements of the MAF sensor.
    • If debris is present, clean the sensor. If the sensor cannot be cleaned, replace the sensor.
  2. Inspect the fuse in the ignition 1 voltage circuit of the MAF sensor.
    • If the fuse is open, test the ignition 1 voltage circuit for a short to ground.
  3. Turn OFF the ignition. Disconnect the MAF/intake air temperature (IAT) sensor. Start the engine.
  4. Observe the MAF/IAT sensor with a scan tool for 0 Hz.
    • If more than 0 Hz, turn OFF the ignition and inspect the harness for improper routing that is too close to any aftermarket accessories, secondary ignition wires, coils, solenoids, relays or motors.
  5. Turn ON the ignition, with the engine OFF.
  6. Measure the battery voltage with a DMM.
  7. Disconnect the MAF/IAT sensor.
  8. Connect a test lamp between the ignition 1 voltage circuit of the MAF sensor and a good ground.
  9. Connect the DMM to the probe of the test lamp and good ground and measure for battery voltage.
    • If not within 0.5 volt of battery voltage, repair the high resistance or open in the MAF sensor ignition 1 voltage circuit.
  10. Turn OFF the ignition and all accessories for 60 seconds to allow the control module to power down.
  11. Measure for 5 ohms of resistance from the ground circuit of the MAF sensor to a good ground with a DMM.
    • If the resistance is more than 5 ohms, repair the high resistance or the open in the MAF sensor ground circuit.
  12. Turn ON the ignition, with the engine OFF.
  13. Measure for 4.8-5.2 volts from the signal circuit of the MAF sensor to a good ground with a DMM.
    • If more than 5.2 volts, test the circuit for a short to voltage or faulty control module.
    • If less than 4.8 volts, test the circuit for an open, short to ground or a faulty control module.
  14. Turn OFF the ignition and connect the J 38522Β  to the signal circuit of the MAF sensor and a good ground.
  15. Set up the variable speed generator. Use the switches to set the duty cycle to normal, the frequency to 5 K and the signal switch to 5 volts.
  16. Start the engine and observe the MAF sensor parameter for 4,950-5,025 Hz with a scan tool.
    • If the MAF sensor is not within the specified parameter range, test for intermittent or poor connection at the control module. If tests OK, replace the control module.
    • If the MAF sensor is within the specified parameter range, test for intermittent or poor connection at the MAF sensor. If tests OK, replace the MAF 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.