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HOMESERVICE MANUALSGMC2020ACADIA SLE, 2.5L ENG VIN AREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 12 (AUTOMATIC TRANSMISSION - 6T50 (M2D) - DIAGNOSTIC INFORMATION AND PROCEDURES)DIAGNOSTIC INFORMATION AND PROCEDURESROAD TESTELECTRICAL FUNCTION CHECK
2020 GMC Acadia SLE, 2.5L Eng VIN A

Electrical Function Check

2020 GMC Acadia SLE, 2.5L Eng VIN ASECTION Electrical Function Check
WARNING: This page is about a different car, the 2019 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.

Perform this procedure first in order to ensure the electronic transmission components are functioning properly. If these components are not checked, a simple electrical condition could be misdiagnosed.

  1. Connect the scan tool.
  2. Ensure the gear selector is in PARK and set the parking brake.
  3. Start the engine.
  4. Verify that the following scan tool data can be obtained and is functioning properly.

    Refer to Control Module References for typical data values. Data that is questionable may indicate a concern.

    • Engine Speed
    • Transmission ISS
    • Transmission OSS
    • Vehicle Speed
    • IMS
    • Commanded Gear
    • Gear Ratio
    • Line PC Sol. Pressure Cmd.
    • Brake Switch
    • ECT, Engine Data List
    • Trans. Fluid Temp.
    • TCM Temperature
    • Calc. Throttle Position
    • Ignition Voltage
    • TFP Switch 1
    • TFP Switch 3
    • TFP Switch 4
    • TFP Switch 5
    • PC Sol. 2 Pressure Cmd.
    • PC Sol. 3 Pressure Cmd.
    • PC Sol. 4 Pressure Cmd.
    • PC Sol. 5 Pressure Cmd.
    • Shift Solenoid 1
    • Shift Solenoid 2
    • TCC PC Sol. Duty Cycle
    • TCC Slip Speed
  5. Check the garage shifts.
    1. Apply the brake pedal and ensure the parking brake is set.
    2. Move the gear selector through the following ranges:
      • PARK to REVERSE
      • REVERSE to NEUTRAL
      • NEUTRAL to DRIVE
      • DRIVE to REVERSE
      • REVERSE to DRIVE
    3. Pause 2 to 3 seconds in each gear position.
    4. Verify the gear engagements are immediate (less than 2 seconds to complete if transmission fluid temperature is above 20°C (68°C) and not harsh. Note that these shifts may be almost imperceptible in some applications. Using the scan tool to monitor Transmission ISS achieving 0 rpm can be used to check delay in these cases.
    6. NOTE:

    Harsh engagement may be caused by any of the following conditions:

    • High engine idle speed - Compare engine idle speed to desired idle speed.
    • Incorrect line pressure - Investigate Line PC Sol. Pressure Cmd. kPa (psi), also perform Line Pressure Check .
    • A default condition caused by certain DTCs that result in maximum line pressure to prevent clutch slippage.
    • Incomplete adapting or incorrect adapting - Repeat maneuver multiple times to see if shift quality improves. If it does not, refer to the service procedures for Harsh Garage Shift .
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.