my Toyota Highlander Fourth Generation (2020-present) transmission slips when I accelerate what's wr...

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, fluid catch pan, transmission fluid.
• Safely lift the vehicle using a jack and secure it with jack stands.
• Allow the engine to cool before proceeding with any work.

2. Check and Replace Transmission Fluid

• Sub-steps:
  1. Locate the transmission dipstick (if equipped) or access the fill plug.
  2. Remove the dipstick and check the fluid level; if low, proceed to add fluid.
  3. If the fluid is burnt or discolored, drain the transmission fluid using a catch pan.
     • Use a socket set to remove the transmission pan bolts.
     • Allow old fluid to completely drain.
  4. Replace the old fluid with new, manufacturer-recommended transmission fluid, refilling it through the dipstick tube or fill plug.
  5. Replace the transmission pan and torque the bolts to the manufacturer’s specifications.

3. Inspect and Replace Transmission Filter

• Sub-steps:
  1. Remove the transmission pan (if not done in the previous step).
  2. Locate and remove the transmission filter using a socket set.
  3. Install the new transmission filter, ensuring it is seated properly.
  4. Reinstall the transmission pan with a new gasket if necessary, torquing the bolts to specifications.

4. Test Transmission Solenoids

• Sub-steps:
  1. Disconnect the electrical connectors from the transmission solenoids.
  2. Use a multimeter to test the resistance of each solenoid according to the specifications in the service manual.
  3. Replace any faulty solenoids with new ones.

5. Road Test

• Sub-steps:
  1. Start the vehicle and let it warm up to operating temperature.
  2. Shift through all gears and monitor for slipping or shifting issues.
  3. Check for any leaks around the transmission area after the test.