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 MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 460 (ENGINE CONTROLS AND FUEL - 3.6L - DTC P0008 TO DTC P0193)DTC P0101CIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G3500, Van Passenger Extended
Circuit/System Testing
2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION 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.
- Inspect for the following conditions:
- An engine vacuum leak
- An air leak in the intake air duct between the mass air flow (MAF) sensor and the throttle body
- A plugged or collapsed intake air duct
- Objects that block the MAF sensor air inlet
- An air filter element that is restricted
- The hydro-carbon absorber in the air cleaner assembly for ruptures or deterioration.
- A restricted throttle plate or for carbon build-up around the throttle plate
- An unseated engine oil dip stick
- A loose or missing engine oil fill cap
- An over filled crankcase
- If you find any of the above conditions, repair as necessary.
- Ignition OFF, disconnect the harness connector at the MAF sensor.
- Ignition OFF, test for less than 5 Ξ© between the ground circuit terminal C and the battery ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Ignition ON, load test the ignition circuit for B+ between terminal B and ground.
- If less than the specified value, test the ignition circuit for an open/high resistance.
- Test for 4.8-5.2 V between the signal circuit terminal A and the ground circuit terminal C.
- If less than the specified range, test the signal circuit for an open/high resistance or a short to ground. If the circuit/connections test normal, replace the ECM.
- If greater than the specified range, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Ignition OFF, connect the red lead of the J 38522Β to the signal circuit terminal A at the MAF/IAT sensor harness connector. See Special Tools . Connect the battery voltage supply to B+, and ground the black lead.
- Set the J 38522Β Signal switch to 5 V, the Frequency switch to 5K, and the Duty Cycle switch to Normal. See Special Tools .
- Ignition ON, observe the scan tool MAF Sensor frequency parameter. The parameter should be between 4,950-5,025 Hz.
- If the parameter is not within the specified range, replace the ECM.
- If all circuits/connections test normal, replace the MAF sensor.
CAUTION:
Do NOT use the low reference circuit in the component harness connector for this test. Damage to the control module may occur due to excessive current draw.
RENDER: 1.0x
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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.