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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1076 (ENGINE CONTROLS AND FUEL - 6.6L (LMM) - DTC P154B TO DTC P2693)DTC P2453CIRCUIT/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 2007 GMC Sierra, 2007 GMC Cab & Chassis Sierra, 2007 Chevrolet Silverado, and 2007 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
    IMPORTANT: Perform the Repair Verification after completing the Circuit/System Testing.
  1. Verify the integrity of the DPF system by visually and physically inspecting any of the following conditions:
    • Any damaged exhaust system components
    • Loose or improperly installed exhaust system components.
    • Restrictions in the exhaust differential pressure sensor ports
    • Damaged, bent, or kinked exhaust differential pressure lines-The lines should not be modified and should have a continuous downward gradient from the sensor.
    • Inspect for fuel contaminates. Refer to Contaminants-in-Fuel Diagnosis .
  2. Verify the integrity of the entire air induction system by inspecting for the following conditions:
    • A loose air inlet duct
    • A loose turbocharger air inlet clamp
    • A damaged air cleaner housing
    • A missing or damaged air cleaner restriction indicator
    • A loose, leaking, or cracked intake manifold air resonator
  3. Remove and inspect the flexible part of the exhaust differential pressure lines for internal restrictions.
    • If a condition is found replace the exhaust pressure line.
  4. Ignition OFF, disconnect the harness connector at the exhaust differential pressure sensor.
  5. Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal 1 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.
  6. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 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.
  7. Verify the scan tool Particulate Filt. Pressure Variance parameter is greater than 98 kPa.
    • If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
  8. Install a jumper wire between the low reference circuit terminal 1 and signal circuit terminal 2. Verify the scan tool Particulate Filt. Pressure Variance parameter is less than -13.0 kPa.
    • If greater 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 ECM.
  9. Ignition OFF for 90 seconds, disconnect the X1 harness connector at the ECM.
  10. Test for less than 5 ohms of resistance on each of the exhaust differential pressure (DPS) sensor circuits between the following terminals:
    • ECM X1 5-volt reference circuit terminal 14 to DPS terminal 3
    • ECM X1 signal circuit terminal 43 to DPS terminal 2
    • If greater than the specified range, repair the open/high resistance in the affected circuit.
  11. If all circuits, the exhaust system, fuel system, air intake, and the differential pressure lines test normal, test or replace the exhaust differential pressure 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.