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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1801 (ENGINE CONTROLS AND FUEL - 4.4L - DTC P0010 TO DTC P0158)DTC P0101 OR P1101CIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6

Circuit/System Testing

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2009 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
  1. Visually and physically inspect the by-pass valve and cable for any of the following conditions:
    • A binding or sticking when opening or closing
    • An incorrectly adjusted cable
  2. Verify the integrity of the entire supercharger air induction system by inspecting for the following conditions:
    • A restricted or collapsed air intake duct
    • A misaligned or damaged air intake duct
    • A dirty or deteriorating air filter element
    • Any objects blocking the air inlet probe of the MAF/IAT sensor
    • Any contamination or debris on the sensing elements in the probe of the MAF/IAT sensor
    • Any water intrusion in the induction system
    • Any unmetered air downstream of the MAF/IAT sensor
    • An intake manifold leak
    • Any snow or ice build up at the air cleaner or MAF/IAT sensor
    • A SCIAP sensor vacuum hose that is missing or damaged
    • A MAP sensor vacuum hose that is missing or damaged
  3. Ignition OFF and scan tool disconnected, disconnect the harness connector at the MAF sensor.
  4. Ignition OFF for 90 seconds, test for less than 5 ohms between the ground circuit terminal B and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  5. Ignition ON, test for 4.8-5.2 volts between the MAF sensor signal circuit terminal A and ground.
    • If less than the specified range, test the MAF sensor 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 MAF sensor signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  6. Ignition ON, verify that a test lamp illuminates between the MAF sensor ignition 1 voltage circuit terminal C and ground.
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  7. Ignition OFF, connect the read lead of J 38522  to the signal circuit terminal A at the MAF/IAT sensor harness connector. Connect the battery voltage supply to B+. Connect the black lead to ground.
  8. Set the J 38522  signal to 5 volts, the Frequency to 5K, and the Duty Cycle to Normal.
  9. Engine idling, observe the scan tool MAF Sensor parameter. The scan tool MAF Sensor parameter should be between 4,950-5,025 Hz.
    • If the MAF Sensor parameter is not within the specified range, replace the ECM.
  10. If all circuits test normal, test or 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:

  • • 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.