FAULTBASE
NEWSASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/Toyota/Corolla/E170 (2013-2019)/how to diagnose the U0101 code on my Toyota Corolla E170 (2013-2019)?

how to diagnose the U0101 code on my Toyota Corolla E170 (2013-2019)?

Toyota Corolla E170 (2013-2019)

Severity: highDifficulty: mediumError Code: U01012-4 hours
3 min read
539 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix U0101 communication issue in Toyota Corolla E170. Step-by-step guide with diagnostic procedures and repair instructions.

Error Code
U0101
Component
Electrical
Repair Time
2-4 hours

Safety Warnings

  • ⚠Disconnect the battery before working on electrical systems to avoid shorts.
  • ⚠Allow the vehicle to cool before performing inspections on engine components.

Symptoms

  • •Check engine light illuminated
  • •Transmission shifting issues or erratic behavior
  • •Engine stalling or misfiring
  • •Loss of power or acceleration
  • •Poor fuel economy

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm U0101 and check for any additional related codes.
  2. 2Inspect the vehicle's wiring harness and connectors between the ECM and TCM for any signs of damage, corrosion, or loose connections.
  3. 3Check the vehicle's battery voltage and ground connections to ensure proper electrical supply to the ECM and TCM.
  4. 4Perform a visual inspection of fuses related to the engine and transmission control modules.
  5. 5Clear the U0101 code and perform a road test to see if the code returns or if any symptoms persist.
  6. 6If the code returns, further test the TCM using a multimeter to ensure it is receiving power and ground signals as specified in the service manual.

Solution

Solution

1. Preparation

  • Gather necessary tools and parts.
  • Disconnect the negative battery terminal to prevent electrical shorts.
  • Ensure the vehicle is on a flat surface and set the parking brake.

2. Inspect Wiring and Connectors

  • Remove the engine cover if necessary for access.
  • Carefully inspect the wiring harness between the ECM and TCM for any visible damage or wear.
  • Disconnect the connectors at both the ECM and TCM. Check for bent pins or corrosion. Clean contacts if necessary.
  • Reconnect the connectors securely ensuring a tight fit.

3. Test Electrical Supply

  • Reconnect the battery and turn the ignition to the "ON" position without starting the engine.
  • Using a multimeter, check the voltage at the TCM connector; it should read between 12V to 14V.
  • Test the ground connections; ensure they are providing a solid ground.

4. Replace Damaged Components

  • If any damaged wires or connectors were found during inspection, replace them with OEM parts.
  • If the TCM is found to be faulty during testing, replace it as per the manufacturer's specifications.

5. Final Assembly

  • Reconnect all electrical connectors and ensure they are secure.
  • Replace any covers that were removed.
  • Reconnect the negative battery terminal.

Verification

After completing the repair, verify that the issue has been resolved:

  • Test the affected component to ensure it functions correctly
  • Check for any error codes or warning lights
  • Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

  • •Follow the manufacturer's recommended maintenance schedule
  • •Address warning signs early before they develop into major issues
  • •Use quality parts and fluids recommended for your vehicle
  • •Keep detailed records of all repairs and maintenance

Tools & Equipment Required

  • OBD-II scanner
  • Multimeter
  • Socket set
  • Screwdrivers

Parts Required

  • Replacement wiring or connectors (if damaged)
  • TCM (if found faulty)

Additional Information

Error CodeU0101
Component

Electrical

Repair Time

2-4 hours

Difficulty

medium

Severity

high

Tools

4 items

Parts

2 items

Related Faults

Discover similar issues

  1. how to reset the maintenance light on my Toyota Corolla E170 (2013-2019)

    Learn how to reset the maintenance light on your 2013-2019 Toyota Corolla E170 with this step-by-step guide. Quick and easy instructions included.

    Component:Electrical
    Symptoms
    • •Maintenance light illuminated on the dashboard
    • •No other performance issues observed
    • +{count} more

  2. how to fix power steering fluid leak in Toyota Corolla E170 (2013-2019)

    Learn how to fix power steering fluid leaks in Toyota Corolla E170 (2013-2019). Step-by-step guide with symptoms, diagnostic steps, and repair instruc...

    Component:Steering
    Symptoms
    • •Power steering warning light illuminated
    • •Difficulty steering, especially at low speeds
    • +{count} more

  3. Gear won't engage Toyota Corolla

    Learn how to diagnose and repair gear engagement issues in a Toyota Corolla E170 (2013-2019) with this comprehensive guide.

    Component:transmission
    Symptoms
    • •The gear lever does not move into gear smoothly
    • •Grinding noise when attempting to shift
    • +{count} more

  4. Fuel filter dirty Toyota Corolla

    P0171

    Learn how to diagnose and replace a dirty fuel filter on a Toyota Corolla E170 (2013-2019) with step-by-step instructions, tools required, and safety ...

    Component:fuel filter
    Symptoms
    • •Engine Misfires or Hesitates
    • •Stalling
    • +{count} more

  5. why is my Toyota Corolla E170 (2013-2019) steering column loose?

    Learn how to diagnose and fix a loose steering column in a 2013-2019 Toyota Corolla E170. Step-by-step guide with symptoms, diagnostic steps, and repa...

    Component:Steering
    Symptoms
    • •Loose or wobbly steering wheel
    • •Increased play in the steering response
    • +{count} more

  6. how to align the steering on Toyota Corolla E170 (2013-2019)?

    Learn how to align the steering on a 2013-2019 Toyota Corolla E170. Step-by-step guide with diagnostic procedures and repair instructions.

    Component:Steering
    Symptoms
    • •Vehicle pulls to the left or right when driving straight
    • •Steering wheel is off-center when the vehicle is moving straight
    • +{count} more

Share this solution

Comments

Sign in to share your thoughts

Sign In

No comments yet

Be the first to share your thoughts

Back to Generation