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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls - 6.6L - Troubleshooting & Diagnosis) >> Fuel Injector Balance Test with Tech 2 (Automatic Transmission) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
IMPORTANT: If any DTCs other than DTC P0300-P0308 are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  1. Start and run the engine until the engine coolant temperature (ECT) is more than 82°C (180°F).
  2. Turn OFF all accessories.
  3. Perform the fuel pressure regulator test, refer to Fuel Pressure Regulator Diagnosis .
  4. Apply the parking brake and place the transmission in Drive.
  5. Hold the brake pedal in the fully applied position. A hiss will be noticeable when the brake is fully applied.
  6. Idle the engine for more than 30 seconds.
  7. Observe the Balancing Rate parameters with a scan tool and record the values for Cylinders 1-8.
  8. Repeat steps 4-7 with the transmission in Neutral.
    • Balance Rates should be between +4 mm3 and -4 mm3 in Neutral or Park and between +6 mm3 and -6 mm3 in Drive. Perform the Cylinder Power Balance Test in Special Functions if not within the specifications.
  9. Record any cylinders that indicate a different cylinder power contribution and compare the Balance Rates previously recorded with the Cylinder Power Balance results.
    • If the Balance Rates were not high or the Cylinder Power Balance test did not indicated a cylinder with a different power contribution, refer to Diagnostic Aids .
    10. IMPORTANT: A fuel injector leak into the combustion chamber may result in mechanical damage to the cylinder. If any fuel spray comes out of a glow plug hole during the compression test, replace the fuel injector of the affected cylinder.
  10. Perform the engine compression test. Refer to Engine Compression Test .
    11. IMPORTANT:
    • Refer to Injection System Components in Engine Controls Component Views . Failure to correctly identify the cylinder positions may result in the replacement of the wrong fuel injector.
    • During replacement of the injectors, inspect the inlet and outlet fittings for corrosion or contamination. Refer to Contaminants-in-Fuel Diagnosis .
  11. If the engine did not have low compression on any of the cylinders, replace the fuel injectors on the cylinders that had poor cylinder power contribution, high balance rates, or a noise/smoke change during cancellation. Refer to Fuel Injector Replacement (Left) or Fuel Injector Replacement (Right) .
  12. Operate the vehicle under the conditions in which the concern occurred.
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