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 2010 GMC Sierra and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Crank the engine while observing the scan tool Vehicle DTC Information.
    • If any of the following DTCs are set, diagnose these first: DTC P0117, P0118, P0122, P0123, P0201-P0208, P0222, P0223, P0335, P0336, P0351-P0358, P0513, P0562, P0563, P0601-P0604, P0606, P0607, P062F, P0633, P0685, P0690, P1516, P1631, P1682, or P2610. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  2. With the ignition ON and the engine OFF, test the fuses that are supplied ignition 1 voltage by the powertrain relay. The test lamp should illuminate ON for each test point of the fuses.
  3. Crank the engine while observing the scan tool engine speed parameter.
  4. Install a spark plug tester onto one ignition module/coil assembly, on each bank of the engine.
  5. NOTE: An erratic or weak spark is considered a no spark condition.
  6. Crank the engine while observing both spark plug testers. Both spark plug testers should spark.
  7. With the ignition ON and the engine OFF, command the fuel pump ON and OFF with the scan tool. The fuel pump should energize when commanded ON, and de-energize when commanded OFF.
  8. Turn OFF the ignition.
  9. Install the J 34730-1AΒ  Fuel Pressure Gauge. With the ignition ON and the engine OFF, command the fuel pump ON several times with the scan tool. Refer to Fuel System DiagnosisΒ  for the fuel pressure specification.
  10. Inspect for the following conditions:
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.