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Home >> GMC >> 2021 >> Acadia AT4 >> Repair and Diagnosis >> External Pages >> Different car >> Section 413 (Automatic Transmission - 9T60 (M3G) Or 9T65 (M3W) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P187E, P18AA-P18AE, P27EC, or P27F0 >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2023 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify the condition does not exist: Incorrect fluid level or condition - Transmission - 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 
  2. Verify there are no related DTCs set in the following system:
    • B315A Transmission Range Control Valve 1 Position Switch
    • B315B Transmission Range Control Valve 2 Position Switch
    • B316 Transmission Park Valve Position Switch
    • Go to next step: If a related DTC is not set 
  3. Verify DTC P18AB & P18AD is not set.
    • If DTC P18AB & P18AD is set 
    1. Verify the condition does not exist: Transmission Fluid Pressure = Less than 345 kPa (50 PSI) - Refer to: Line Pressure Check 
      • If 345 kPa (50 PSI) or greater - Refer to: Diagnostic Fault Information
    • Go to next step: If DTC P18AB & P18AD is not set 
  4. Verify DTC P187E is not set.
    • If DTC P187E is set 
    1. Verify the condition does not exist: Mechanical Condition@Mode Valve Position SwitchorPark Servo Piston Switch
      • If a condition exists - Repair or replace as necessary
      • Go to next step: If no conditions exist

        Go to next step: Refer to: Diagnostic Fault Information & Repair or replace as necessary

    • Go to next step: If DTC P187E is not set 
  5. Ignition - On/Vehicle - In Service Mode
  6. Perform the following action: Clear the DTCs.
  7. 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 DTC P187E, P18AA, P18AB, P18AC, P18AD, P18AE, P27EC, P27F0, P27EB, P27ED, P27EE, P27EF, P27F1, P27F2 is not set.

    • If DTC P27EB, P27ED, P27EE, P27EF, P27F1, P27F2 is set 

      Refer to: Diagnostic Trouble Code (DTC) List - Vehicle

    • If DTC P187E, P18AA, P18AB, P18AC, P18AD, P18AE, P27EC, P27F0 is set 

      Refer to: Diagnostic Fault Information & Repair or replace as necessary

    • Go to next step: If none of the DTCs are set 
  8. All OK.
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