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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Automatic Transmission - 6T50 (M2D) - Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> DTC P0776 Or P0777: Pressure Control Solenoid Valve 2 Stuck Off/On - Transmission Hydraulic/Mechanical Performance >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
    NOTE:

    You must perform the Circuit/System Verification first.

  1. Engine idling at the normal operating temperature.
  2. Verify the transmission line pressures are within the specified range. Refer to Line Pressure Check , and Solenoid Valve Pressure (Gen 3) .
    • Go to next step: If the pressures are within range 
  3. Ignition OFF, remove the Q8 Control Solenoid Valve Assembly.
  4. Verify the pressure changes for all solenoids when performing the solenoid test. Refer to Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test .
    • If the pressure does not change 

      Replace the Q8 Control Solenoid Valve Assembly.

    • Go to next step: If the pressure changes 
  5. Verify the mechanical conditions listed below do not exist. Repair or replace as necessary.

DTC P0776 or P0777 - Control Valve Body Assembly

DTC P0776 - 3-5-R and 4-5-6 Clutch Housing Assembly 

3-5-R clutch backing plate retaining ring not seated, causing clutch pack over-travel.

DTC P0776 or P0777 - Torque Converter (w/Fluid Pump) Housing Assembly 

Fluid pump housing/gear damaged/scored.

DTC P0776 - Channel Plate and Spacer Plate 

Oil channels or orifices blocked by debris.

DTC P0776 or P0777 - Q8 Control Solenoid Valve Assembly