my Toyota Highlander XU70 (2020-Present) has a check engine light and code P0700, what does it mean

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, socket set, and torque wrench.
• Ensure the vehicle is parked on a level surface and the engine is turned off.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Transmission Fluid

• Sub-step 1: Remove the transmission fluid dipstick and check the fluid level.
• Sub-step 2: If low, locate the transmission fluid fill plug and add the appropriate type of transmission fluid as specified in the owner’s manual (typically Toyota ATF WS).
• Sub-step 3: If contaminated, drain the old fluid using a wrench to remove the drain plug and replace it with new fluid.

3. Check and Repair Electrical Connections

• Sub-step 1: Locate the TCM; it is usually near the transmission.
• Sub-step 2: Disconnect the wiring harness from the TCM and inspect for corrosion or bent pins.
• Sub-step 3: Clean any corrosion with electrical contact cleaner and reconnect the harness. If damaged, replace the wiring harness.

4. Replace TCM (if necessary)

• Sub-step 1: If the TCM is found faulty during testing, remove it by unscrewing the mounting bolts.
• Sub-step 2: Disconnect the electrical connectors carefully.
• Sub-step 3: Install the new TCM by connecting the electrical connectors and securing it with bolts to the mounting bracket. Torque to manufacturer specifications.

5. Reconnect Battery and Clear Codes

• Sub-step 1: Reconnect the battery terminals, ensuring they are tight.
• Sub-step 2: Use the OBD-II scanner to clear the P0700 code and any other related codes.
• Sub-step 3: Start the engine and allow it to idle for a few minutes.