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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench.
• Ensure the vehicle is parked on a level surface and the engine is off before beginning work.
• Disconnect the battery to prevent electrical shorts.

2. Check Transmission Fluid

• Locate the transmission dipstick (if applicable).
• Remove the dipstick and wipe it clean, then insert it back and remove it again to check the fluid level.
• If fluid is low, add the recommended type of transmission fluid (typically Toyota ATF WS).
• If fluid is dark or smells burnt, plan for a transmission fluid change.

3. Inspect Wiring and Connectors

• Visually inspect the wiring harness connected to the TCM and transmission for any signs of wear, frays, or corrosion.
• Disconnect the connectors and clean them, ensuring a tight fit when reconnected.
• Repair or replace any damaged wires or connectors as necessary.

4. Test TCM Operation

• Reconnect the battery and use a multimeter to check voltage at the TCM connector.
• Ensure the TCM is receiving the necessary 5V or 12V power supply as specified in the service manual.
• If the TCM does not receive proper voltage, trace the circuit back to the power source.

5. Replace TCM (if necessary)

• If the TCM is determined to be faulty, it will need to be replaced.
• Remove any components obstructing access to the TCM.
• Disconnect the wiring harness and remove the mounting bolts using the socket set.
• Install the new TCM by reversing the removal steps, ensuring all connections are secure.