how to diagnose P0700 code on my Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is off.
• Disconnect the battery to prevent electrical shorts.

2. Fluid Inspection and Replacement

• Sub-steps:
  • Locate the transmission dipstick and check fluid level; add ATF if low.
  • If fluid is dark or smells burnt, drain the transmission fluid using a suitable pan.
  • Replace the transmission filter if applicable.
  • Refill the transmission with the manufacturer's recommended ATF type, ensuring it’s at the correct level.

3. Wiring and Connector Inspection

• Sub-steps:
  • Remove any protective covers to access the transmission wiring harness.
  • Inspect connectors for corrosion or damage; clean or replace as necessary.
  • Ensure all connectors are securely attached.

4. Transmission Control Module (TCM) Testing

• Sub-steps:
  • Reconnect the battery.
  • Use a multimeter to check the voltage and ground at the TCM connector.
  • If readings are outside specifications, consider replacing the TCM.

5. Reassemble and Test

• Sub-steps:
  • Reassemble any components that were removed during the inspection.
  • Clear any stored trouble codes using the OBD-II scanner.
  • Test drive the vehicle to verify that the transmission operates smoothly and check for any reoccurring codes.