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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1733 (Automatic Transmission - 6L45/6L50/6L80/6L90 - DTC P0218 To DTC P0974) >> DTC P0741 or P0742 >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
    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. Engine idling in Park, verify with a scan tool the Transmission ISS/OSS supply voltage test status parameter displays OK.
  4. 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.
  5. 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.
  6. NOTE: Perform a scan tool snapshot, during the road test.
  7. Perform the Road Test . Verify the transmission operation performs as indicated, in the road test instructions.
  8. Review the Tech 2 snapshot transmission data parameters. Verify the engine and transmission data parameters display the correct values in all forward gear ranges:
    • Engine Speed
    • Engine Coolant Temperature
    • Transmission ISS
    • Transmission OSS
    • Vehicle Speed
    • Transmission Fluid Temperature
    • Brake Pedal Switch
    • TCC Pressure Control Solenoid Valve Pressure Command
    • TCC Duty Cycle
    • TCC Slip Speed
  9. 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.