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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 362 (Automatic Transmission - 6L80/6L90 - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0776 or P0777 >> Circuit/System Verification

Circuit/System Verification

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    NOTE:

    If other DTCs are set, diagnose those DTCs first.

  1. Engine idling in Park, with parking brake applied and drive wheels chocked.
  2. Perform the Transmission Fluid Level and Condition Check  to verify correct fluid level and condition.
  3. Monitor the Transmission Fluid Pressure (TFP) switch 1 with a scan tool. Place the gear select lever in Park, Reverse, and Neutral range. Verify the TFP switch 1 parameter states are correct for Park, Reverse, and Neutral. Refer to Transmission Fluid Pressure Switch Logic .
  4. Place the gear select lever in Drive range. Command the shift transmission with a scan tool through all forward ranges. Verify the TFP switch 1 parameter states are correct for all forward ranges. Refer to Transmission Fluid Pressure Switch Logic .
  5. Engine idling in Park, verify with a scan tool the Transmission ISS/OSS supply voltage test status parameter displays OK.
  6. Engine idling in Park. Observe the Transmission ISS parameter on the scan tool, while varying the engine speed. The Transmission ISS parameter should vary with engine speed and not drop out.
  7. Operate the vehicle at 16-32 km/h (10-20 mph) while observing the Transmission OSS parameter on the scan tool. The Transmission OSS parameter should vary with the vehicle speed and not drop out.
    8. NOTE:

    Perform a scan tool snapshot, during the road test.

  8. Perform the Road Test . Verify the transmission operation performs as indicated in the road test instructions.
  9. Review the scan tool snapshot data. Verify the following transmission data parameters display the correct values for each gear range:
    • Transmission ISS
    • Transmission OSS
    • PC Solenoid 2
    • TFP Switch 1
  10. Operate the vehicle within the Condition for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
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