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Home >> GMC >> 2021 >> Terrain SLE, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 247 (Automatic Transmission - 6T40 (MNH MNK) Or 6T45 (MHG) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0634 >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2021 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
    WARNING:

    Refer to Parking Brake and Drive Wheels Warning .

  1. Ignition - On / Vehicle - In Service Mode
  2. Verify the scan tool Freeze Frame/Failure Records parameter: Engine Coolant Temperature = Colder than 125°C (257°F)
    • Go to next step: If colder than 125°C (257°F) 
  3. Verify the scan tool parameter: TCM Temperature = -39 to 139°C (-38 to 282°F)
    • If not between -39 and 139°C (-38 and 282°F) 

      Replace the component: Q8 Control Solenoid Valve Assembly

    • Go to next step: If between -39 and 139°C (-38 and 282°F) 
  4. Verify the following parameters are within 8°C (14°F) of each other:
    • TCM Temperature
    • TCM Power-Up Temperature
    • If not within 8°C (14°F) of each other 

      Replace the component: Q8 Control Solenoid Valve Assembly

    • Go to next step: If within 8°C (14°F) of each other 
  5. Engine - Idling
  6. Transmission - Park
  7. Test for 12.6 to 15 V between the test points: Battery Positive Post & Battery Negative Post
    • Go to next step: If between 12.6 and 15 V 
  8. Verify the condition does not exist: Incorrect fluid level or condition. Refer to: Transmission Fluid Level and Condition Check 
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists 
  9. Clear the DTCs.
  10. Road test the vehicle. Refer to: Road Test 

    Verify the scan tool parameter: Transmission Fluid Temperature = Colder than 140°C (284°F)

    • If 140°C (284°F) or warmer 
    1. Ignition/Vehicle - Off
    2. Verify the component location is free of debris, clutter or any obstruction that may reduce airflow which could cause an overheat condition: Radiator
      • If a condition exists - Repair or replace as necessary
      • Go to next step: If no condition exists
    3. Verify the condition does not exist:
      • Radiator - Visible Damage
      • Transmission Fluid Cooler - Visible Damage
      • Transmission Fluid Cooler Pipe - Kinked or Visible Damage
      • If a condition exists - Repair or replace as necessary
      • Go to next step: If none of the conditions exists
    4. Verify the condition does not exist: Transmission Fluid Cooler & Transmission Fluid Cooler Pipe - Blocked by debris
      • If a condition exists - Repair or replace as necessary
    • Go to next step: If colder than 140°C (284°F) 
  11. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

    Verify the DTC does not set.

    • If the DTC sets 

      Replace the component: Q8 Control Solenoid Valve Assembly

    • Go to next step: If the DTC is not set 
  12. All OK.
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