why does my Toyota Highlander Third Generation (2014-2019) feel like it's slipping gears

Toyota Highlander Third Generation (2014-2019)

Error Codes

3-5 hours

Time

medium

Difficulty

high

Severity

3 min read

494 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 transmission slipping issues in Toyota Highlander 2014-2019. Step-by-step guide with diagnostic procedures and repair instructions.

Affected Component

Transmission

Estimated Time

3-5 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the engine to cool before working on the transmission.

Symptoms

•Engine RPM increases without a corresponding increase in vehicle speed
•Delayed or harsh shifting between gears
•Unusual noises when shifting (e.g., grinding or whining)
•Warning lights illuminated on the dashboard (e.g., check engine light)
•Fluid leaks under the vehicle
•Burning smell from the transmission area

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify any transmission-related trouble codes.
2
Check the transmission fluid level and condition; look for discoloration or a burnt smell.
3
Inspect the transmission fluid cooler lines for leaks or blockages.
4
Test the transmission solenoids for proper function using a multimeter.
5
Check for any software updates or recalls that may affect transmission performance.
6
Inspect the throttle position sensor and mass airflow sensor for proper operation.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

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
•Socket set
•Funnel
•Fluid catch pan
•Multimeter

Parts Required

•Transmission fluid (Toyota ATF WS)
•Transmission filter (if applicable)
•Transmission solenoids (if faulty)

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Symptoms

•Engine RPM increases without a corresponding increase in vehicle speed

•Delayed or harsh shifting between gears

•Unusual noises when shifting (e.g., grinding or whining)

•Warning lights illuminated on the dashboard (e.g., check engine light)

•Fluid leaks under the vehicle

•Burning smell from the transmission area

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify any transmission-related trouble codes.
2
Check the transmission fluid level and condition; look for discoloration or a burnt smell.
3
Inspect the transmission fluid cooler lines for leaks or blockages.
4
Test the transmission solenoids for proper function using a multimeter.
5
Check for any software updates or recalls that may affect transmission performance.
6
Inspect the throttle position sensor and mass airflow sensor for proper operation.

Solution

1. Preparation

Gather necessary tools and parts.
Park the vehicle on a level surface and engage the parking brake.
Disconnect the negative battery terminal to prevent electrical issues.

2. Check and Change Transmission Fluid

Tools Required: Socket set, funnel, fluid catch pan.
Remove the transmission pan using a socket set to access the fluid.
Drain the old fluid into a catch pan.
Replace the transmission filter if equipped.
Reinstall the pan with new gasket and torque to manufacturer specifications (typically around 10-12 ft-lbs).
Fill the transmission with new fluid through the dipstick tube according to the manufacturer's specifications (typically Toyota ATF WS).

3. Inspect and Replace Transmission Solenoids

Tools Required: Socket set, multimeter, replacement solenoids (if needed).
Remove the transmission valve body to access the solenoids.
Disconnect the electrical connectors from the solenoids.
Test solenoids with a multimeter to ensure they are within manufacturer specifications.
Replace any faulty solenoids and reassemble the valve body.

4. Reprogram Transmission Control Module (if applicable)

Tools Required: OBD-II scanner with programming capability.
Using the scanner, follow the manufacturer instructions to reprogram the transmission control module, if necessary.