how to diagnose P0700 code on Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather tools and parts necessary for the repair.
• Ensure the vehicle is on a flat surface, and engage the parking brake.
• Disconnect the battery to ensure safety while working on electrical components.

2. Check Transmission Fluid

• Tools Required: Transmission dipstick, funnel, and appropriate transmission fluid.
• Remove the transmission dipstick and check the fluid level and color.
• If low, add the recommended transmission fluid until the proper level is reached.
• If the fluid is dark or has a burnt smell, consider a transmission fluid change.

3. Inspect and Repair Wiring

• Tools Required: Multimeter, wire strippers, heat shrink tubing.
• Visually inspect the wiring harness connected to the TCM for damage or corrosion.
• Use a multimeter to test continuity of the wires leading to the TCM.
• Repair or replace any damaged wires and ensure all connections are secure.

4. Replace Transmission Control Module (if necessary)

• Tools Required: Socket set, torque wrench, and OBD-II scanner.
• Locate the TCM, typically found near the transmission or under the dashboard.
• Disconnect the harness from the TCM and remove the mounting bolts.
• Install the new TCM, ensuring it is securely mounted and all connections are reattached.
• Torque bolts to manufacturer specifications.

5. Reconnect Battery and Clear Codes

• Reconnect the battery and use the OBD-II scanner to clear any stored trouble codes.
• Perform a road test to ensure the P0700 code does not return and the transmission operates smoothly.