2026-09-01

Heat Exchanger - Rear Drive Unit (4DU) (Remove and Replace)

Correction code 40305232 0.66 NOTE: Unless otherwise explicitly stated in the procedure, the correction code and its associated FRT reflect all of the work required to perform this procedure, including the linked procedures. Do not stack correction codes unless explicitly told to do so. NOTE: See Flat Rate Times to learn more about FRTs and how they are created. NOTE: See Personal Protection to make sure wearing proper PPE when performing the below procedure. NOTE: See Ergonomic Precautions for safe and healthy working practices.

  • 2026-09-01: Removed steps to disconnect/connect the LV power and added oil pump low pressure test routine.
  • 2024-01-10: Corrected spellings of "exchanger".
Warning
This procedure is a DRAFT. Although it has been validated, Warnings and Cautions might be missing. Follow safety requirements and use extreme caution when working on or near High Voltage systems and components.

Remove

  1. Move the vehicle to a 2 post lift. See Raise Vehicle - 2 Post Lift.
  2. Open the LH front door and raise the LH front window.
  3. Enable Service Mode on the touchscreen. See Service Mode.
  4. Unlock the vehicle gateway. See Gateway (Unlock).
  5. Access the thermal system routines on the touchscreen: Touch Quick Controls > Service Mode > Diagnostics > Thermal.
    Note
    Authorize routines by holding the turn signal stalk full up (right hand turn) while applying brake with the key in the vehicle.
  6. Touch Start Thermal Fill Drain (Coolant Only) on the touchscreen.
    Note
    Touch the X at the top left of window to close once completed.
    Note
    Verify the indicator displays green and the vehicle is ready for the coolant fill/drain.
    Note
    Thermal "Fill Drain" routine has a 5 hour time limit. After 5 hours, the routine must be performed again.
  7. Remove the rear underhood apron. See Underhood Apron - Rear (Remove and Replace).
  8. Remove the cabin intake duct. See Duct - Upper - Cabin Intake (Remove and Replace).
  9. Remove the rear aero shield panel. See Panel - Aero Shield - Rear (Remove and Replace).
  10. Drain the gearbox fluid from the rear drive unit. See Gearbox Fluid - Rear Drive Unit (4DU) (Drain and Refill).
  11. Position the coolant drain collector underneath the RH rear of the HV battery.
  12. Release the clip that attaches the rear drive unit inverter to heat exchanger hose to the rear drive unit heat exchanger.
  13. Release the clip, disconnect the rear drive unit inverter to heat exchanger hose from the rear drive unit heat exchanger, immediately plug the heat exchanger fitting, allow the hose to drain, and then plug the hose fitting.
  14. Release the clip that attaches the rear drive unit outlet hose to the rear drive unit heat exchanger.
  15. Release the clip, disconnect the rear drive unit outlet hose from the rear drive unit heat exchanger, and then immediately plug both fittings.
    Note
    Coolant loss greater than 1 L will require a vacuum fill.
  16. Remove the bolts (x2) that attach the rear drive unit heat exchanger to the rear drive unit, and then remove the heat exchanger from the drive unit.
    Note
    Use of the following tool(s) is recommended:
    • 4 in extension
    • External Torx Plus EP10
    • Ratchet/torque wrench
    Note
    Confirm that the O-rings (x2) are not stuck in the rear drive unit.

Install

  1. Apply a light coat of KAF1 oil to the O-rings of the heat exchanger, and then wipe away any excess oil.
  2. Install the rear drive unit heat exchanger onto the rear drive unit, and then install the bolts (x2) that attach the heat exchanger to the drive unit.
    5 Nm (3.7 lbs-ft) +30 deg
  3. Remove the plugs from the fittings, immediately connect the rear drive unit outlet hose to the rear drive unit heat exchanger, fasten the clip, and then perform a Push-Pull-Push check of the fitting.
  4. Fasten the clip that attaches the rear drive unit outlet hose to the rear drive unit heat exchanger.
  5. Remove the plugs from the fittings, immediately connect the rear drive unit inverter to heat exchanger hose to the rear drive unit heat exchanger, fasten the clip, and then perform a Push-Pull-Push check of the fitting.
  6. Fasten the clip that attaches the rear drive unit inverter to heat exchanger hose to the rear drive unit heat exchanger.
  7. Remove the coolant drain collector from under the vehicle.
  8. Refill the rear drive unit with gearbox fluid. See Gearbox Fluid - Rear Drive Unit (4DU) (Drain and Refill).
  9. Install the mid aero shield panel. See Panel - Aero Shield - Rear (Remove and Replace).
  10. Lower the vehicle fully.
  11. Connect a laptop with Toolbox to the vehicle. SeeToolbox (Connect and Disconnect).
  12. Perform the routine: TEST-SELF_DIR_X_OIL-PUMP-PRESSUREvia Toolbox:(link)
  13. Disconnect the laptop from the vehicle. SeeToolbox (Connect and Disconnect).
  14. Remove the cap from the coolant bottle.
    Note
    Perform this step only for heat pump vehicles.
  15. Inspect the coolant level and add coolant as necessary to bring the fluid level to the Max line.
    Note
    If greater than 1 L of coolant was lost during repair, a vacuum fill is required.
  16. On the vehicle touchscreen, go to Service Mode > Thermal > Stop Thermal Fill/Drain, touch Run and allow the routine to complete.
  17. On the vehicle touchscreen, go to Thermal > Coolant System > Coolant Purge Start, touch Run and wait for the routine to complete (10 minutes).
  18. Add coolant to the reservoir as necessary, and install the reservoir cap.
  19. Install the cabin intake duct. See Duct - Upper - Cabin Intake (Remove and Replace).
  20. Install the rear underhood apron. See Underhood Apron - Rear (Remove and Replace).
  21. Disable Service Mode. See Service Mode.
  22. Raise the LH front window and close the LH front door.
  23. Remove the vehicle from the 2 post lift. See Raise Vehicle - 2 Post Lift.