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Home >> GMC >> 2020 >> Terrain Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1 (Automatic Transmission - 6T40 (MNH) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0776 or P0777 >> Diagnostic Fault Information

Diagnostic Fault Information

WARNING: This page is about a different car, the 2020 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:

The components are listed from the least to the most intrusive to service.

Component DTC Condition
Q8 Control Solenoid Valve Assembly P0776, P0777
  • Q27B Pressure Control Solenoid Valve 2 - Binding or Sticking/Stuck
  • Control Solenoid Valve Assembly Filter Plate - Blocked by debris/Restricted or Cracked
  • O-Ring - Leaking
Control Valve Body P0776, P0777
  • Clutch Regulator Valve - Binding or Sticking/Stuck
  • Control Valve Body Ball Check Valve - Leaking or Blocked by debris
  • Oil Channels or Orifices - Blocked by debris/Restricted
Control Valve Body Spacer Plate P0776 Oil Channels or Orifices - Blocked by debris/Restricted
Control Valve Channel Plate P0776 Oil Channels or Orifices - Blocked by debris/Restricted
3-5-R and 4-5-6 Clutch Housing Assembly P0776
  • 3-5-R Clutch Backing Plate Retaining Ring - Not seated correctly
  • 3-5-R clutch plates worn or damaged.
  • Clutch Housing - Scored/Worn
  • Clutch Piston
    • Cracked
    • Damaged seal.
Torque Converter with Fluid Pump Housing Assembly P0776, P0777
  • Oil Pump Drive Gear - Worn
  • Oil Pump Driven Gear - Worn
  • Transmission Fluid Pump Housing - Scored/Worn