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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is on a flat surface and securely raised with jack stands if necessary.

2. Transmission Fluid Inspection

• Sub-steps:
  1. Remove the transmission dipstick and check the fluid level.
  2. Inspect fluid color and smell; it should be bright red and not burnt.
  3. If the fluid is low, top it off with the manufacturer-recommended transmission fluid.
• Tools Required: Transmission dipstick, funnel for adding fluid.

3. Wiring and Connector Inspection

• Sub-steps:
  1. Locate the TCM, usually found near the transmission or under the dashboard.
  2. Visually inspect the wiring harness for frays, breaks, or corrosion.
  3. Disconnect the TCM connector and check for bent pins or corrosion.
• Tools Required: Screwdriver set for accessing the TCM, flashlight for better visibility.

4. TCM Testing

• Sub-steps:
  1. Reconnect the TCM and use a multimeter to check voltage at the power and ground terminals.
  2. Compare readings with manufacturer specifications; consult the service manual.
  3. If readings are outside normal ranges, replace the TCM.
• Tools Required: Multimeter.

5. Replacing the TCM (if necessary)

• Sub-steps:
  1. Disconnect the battery to prevent electrical shorts.
  2. Remove the TCM mounting screws and carefully detach it from the harness.
  3. Install the new TCM and secure it with screws.
  4. Reconnect the battery and clear the codes using an OBD-II scanner.
• Tools Required: Socket set, OBD-II scanner for code clearing.