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

Solution

1. Preparation

• Gather all necessary tools and parts before beginning the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, fluid pump.

2. Inspect and Replace Transmission Fluid

• Remove the transmission fluid dipstick or fill plug.
• Use a fluid pump to extract the old transmission fluid if necessary.
• Inspect the fluid for discoloration or burning odor; if contaminated, replace with the manufacturer-recommended fluid type.
• Refill with new transmission fluid, ensuring it meets Toyota specifications (typically Toyota ATF WS).
• Check the fluid level with the dipstick and ensure it is within the specified range.

3. Check and Repair Wiring/Connectors

• Inspect the wiring harness leading to the TCM for signs of wear, fraying, or corrosion.
• If damaged, repair or replace the wiring as necessary.
• Ensure all connectors are securely attached and free of debris.

4. Test the Transmission Control Module (TCM)

• Using a multimeter, check the TCM's power and ground signals based on the manufacturer's specifications.
• If the TCM is found to be faulty, it should be replaced with a new unit.
  • Disconnect the TCM connectors.
  • Remove mounting screws and gently pull the TCM from its housing.
  • Install the new TCM, securing it with screws, and reconnect the wiring harness.

5. Reconnect Battery and Test

• Reconnect the negative battery terminal.
• Clear any stored codes from the OBD-II system.
• Start the vehicle and perform a test drive to ensure proper transmission operation.