how to diagnose a P0700 code on my Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Ensure the vehicle is parked on a level surface and the engine is off.
• Gather tools and parts needed for the repair.

2. Check Transmission Fluid

• Remove the transmission dipstick and wipe it clean.
• Reinsert the dipstick and remove it again to check the fluid level.
• If low, add the correct type of transmission fluid as specified in the owner’s manual.
• If the fluid is burnt or contaminated, proceed to the next step.

3. Replace Transmission Fluid and Filter

• Tools Required: Socket set, fluid pump, transmission fluid.
• Sub-steps:
  1. Raise the vehicle and secure it on jack stands.
  2. Remove the transmission pan bolts and carefully lower the pan.
  3. Remove the old filter and replace it with a new one.
  4. Clean the pan and replace the gasket.
  5. Reinstall the pan and torque bolts to manufacturer specifications.
  6. Use a fluid pump to add new transmission fluid through the dipstick tube.

4. Inspect and Repair Wiring

• Visually inspect the wiring harness and connectors to the TCM.
• If any damage is observed, repair or replace the wiring as necessary to ensure a solid connection.

5. Test the TCM

• Tools Required: Multimeter.
• Sub-steps:
  1. Disconnect the TCM from the vehicle.
  2. Use a multimeter to test for power and ground at the connector.
  3. If there is no power, trace back to the fuse or relay.
  4. If power is present, consider replacing the TCM if no other faults are found.