how to diagnose transmission slipping in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent any electrical issues during the repair.

2. Check and Replace Transmission Fluid

• Tools Required: Transmission fluid pump, funnel, socket set, torque wrench.
• Sub-steps:
  1. Locate the transmission dipstick and remove it to check fluid level.
  2. If fluid is low or burnt, drain the old fluid by removing the transmission pan.
  3. Replace the transmission fluid with the manufacturer-recommended type (typically Toyota ATF WS).
  4. Reinstall the transmission pan and torque bolts to specifications (usually around 8-10 ft-lbs).
  5. Refill the transmission fluid through the dipstick tube using the fluid pump.

3. Inspect and Replace Transmission Filter

• Tools Required: Socket set, torque wrench, sealant (if required).
• Sub-steps:
  1. Remove the transmission pan again if already removed or drain the fluid first.
  2. Remove the old transmission filter by unbolting it from the transmission case.
  3. Install a new filter, ensuring it is seated properly.
  4. Reinstall the transmission pan, applying sealant if necessary, and torque bolts to specifications.

4. Check for Mechanical Issues

• Tools Required: Transmission pressure gauge, multimeter.
• Sub-steps:
  1. If slipping persists, connect a transmission pressure gauge to check for pressure anomalies.
  2. If pressure is low, inspect the pump and internal components for wear or damage.
  3. Test electrical components such as solenoids using a multimeter to ensure they are functioning properly.