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

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Ensure the vehicle is parked on a level surface and the parking brake is engaged.
• Disconnect the battery to prevent electrical shorts.

2. Check and Replace Transmission Fluid

• Sub-steps:
  • Locate the transmission dipstick (if equipped) and remove it.
  • Inspect the fluid level. If low, add the manufacturer-recommended transmission fluid.
  • If the fluid is dark or has a burnt smell, a fluid change is necessary.
  • Tools Required: Funnel, transmission fluid (Toyota Type T-IV or equivalent).

3. Inspect and Repair Wiring and Connectors

• Sub-steps:
  • Visually inspect the wiring harness connected to the TCM for any signs of wear or damage.
  • Disconnect the connector and clean the terminals using electrical contact cleaner.
  • If damaged, replace the wiring harness or connector as needed.

4. Test and Replace Transmission Control Module (if necessary)

• Sub-steps:
  • Using a multimeter, check the voltage and ground at the TCM connector.
  • If voltage is absent or inconsistent, the TCM may need replacing.
  • Remove the old TCM by unscrewing any fasteners and disconnecting the wiring.
  • Install the new TCM by reversing the removal process.
  • Tools Required: Screwdriver set, multimeter.

5. Clear Codes and Test Drive

• Sub-steps:
  • Reconnect the battery and use the OBD-II scanner to clear the P0700 code.
  • Start the vehicle and perform a test drive to monitor for any issues.
  • Observe the transmission performance and check for any reoccurrence of the check engine light.