how to fix P0700 code in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

1. Ensure the vehicle is parked on a level surface, and the engine is turned off.
2. Disconnect the negative battery terminal to prevent electrical shorts.
3. Gather tools and parts needed for the repair.

2. Check and Replace Transmission Fluid

1. Remove the transmission fluid dipstick and inspect the fluid color and smell.
2. If fluid is dark or smells burnt, drain the old fluid using a fluid pump.
3. Replace with new transmission fluid as specified in the owner’s manual (e.g., Toyota ATF WS).
4. Recheck fluid levels after filling to the appropriate mark.

3. Inspect and Repair Wiring/Connections

1. Visually inspect the wiring harness leading to the TCM and transmission for signs of damage.
2. Clean any corroded connectors using electrical contact cleaner.
3. Repair or replace damaged wiring as needed to ensure continuity.

4. Test and Replace Transmission Control Module

1. Reconnect the battery and use the OBD-II scanner to clear existing codes.
2. Start the vehicle and check for any return of the P0700 code.
3. If the code persists, remove the TCM from its mounting location.
4. Inspect for damage; if damaged, replace with a new OEM TCM.
5. Reinstall the TCM, ensuring all connections are secure.