how to deal with a BMW X5 F15 (2014-2019) that won't engage in 4WD

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, fluid pump.
• Disconnect the battery to ensure safety while working on electrical components.
• Allow the vehicle to cool before starting the procedure.

2. Fluid Inspection and Replacement

• Sub-steps:
  1. Raise the vehicle using a jack and secure it on jack stands.
  2. Locate the transfer case drain and fill plugs.
  3. Remove the fill plug and check the fluid level. If low, drain the fluid from the drain plug.
  4. Inspect the fluid for metal shavings or contamination; if present, further inspection of the transfer case is necessary.
  5. Refill the transfer case with the manufacturer-recommended fluid (e.g., BMW ATF).
  6. Torque the drain plug to the manufacturer's specifications and replace the fill plug.

3. Transfer Case Motor Inspection

• Sub-steps:
  1. Locate the transfer case motor and disconnect the electrical connector.
  2. Use a multimeter to check for voltage at the connector while activating the 4WD switch.
  3. If no voltage is detected, trace the wiring back to the control module for potential breaks or shorts.
  4. If voltage is present, remove the transfer case motor and inspect for mechanical failure or binding.
  5. Replace the transfer case motor if damaged, ensuring to torque bolts to specifications upon installation.

4. Replace 4WD Control Switch

• Sub-steps:
  1. Disconnect the battery again for safety.
  2. Remove the trim panel around the 4WD control switch.
  3. Disconnect the wiring harness from the switch and replace it with a new switch.
  4. Reassemble the trim panel and reconnect the battery.