why does my Toyota Highlander Third Generation (2014-2019) transmission slip when accelerating

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

3 min read

589 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 in Toyota Highlander 2014-2019. Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

Affected Component

Transmission

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

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

Symptoms

•Check engine light illuminated
•Engine RPM increases without corresponding vehicle speed
•Delayed or harsh shifting between gears
•Unusual noises (grinding or whining) during acceleration
•Poor fuel economy
•Fluid leakage under the vehicle

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify any transmission-related faults.
2
Check the transmission fluid level and condition (color and smell).
3
Inspect the transmission fluid cooler lines for leaks or damage.
4
Examine the transmission filter for clogs or restrictions.
5
Test the vehicle's throttle position sensor (TPS) for proper operation.
6
Inspect the transmission control module (TCM) connections for corrosion or loose wiring.

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
•Transmission fluid pump
•Socket set
•Torque wrench
•Multimeter

Parts Required

•Toyota ATF WS transmission fluid
•Transmission filter
•Gasket for transmission pan
•Throttle position sensor (if needed)

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify any transmission-related faults.
2
Check the transmission fluid level and condition (color and smell).
3
Inspect the transmission fluid cooler lines for leaks or damage.
4
Examine the transmission filter for clogs or restrictions.
5
Test the vehicle's throttle position sensor (TPS) for proper operation.
6
Inspect the transmission control module (TCM) connections for corrosion or loose wiring.

Solution

1. Preparation

Gather necessary tools and parts.
Ensure the vehicle is parked on a flat surface and the engine is off.
Disconnect the battery to prevent any electrical shorts.

2. Check and Replace Transmission Fluid

Tools Required: Transmission fluid pump, funnel, socket set, torque wrench.
Sub-steps:
1. Locate the transmission dipstick; remove and check fluid level.
2. If low, add the recommended transmission fluid (Toyota ATF WS).
3. If fluid is dark or burnt, drain the old fluid using the drain plug.
4. Replace with new transmission fluid, checking the dipstick for proper levels.
5. Torque the drain plug to the manufacturer's specifications.

3. Inspect and Replace Transmission Filter

Tools Required: Socket set, torque wrench, new transmission filter, gasket.
Sub-steps:
1. Remove the transmission pan by unscrewing the bolts.
2. Carefully detach the pan and clean the surfaces.
3. Remove the old filter and replace it with a new one.
4. Install a new gasket and reattach the transmission pan, torquing the bolts to specifications.

4. Inspect and Test the Throttle Position Sensor (TPS)

Tools Required: Multimeter, socket set.
Sub-steps:
1. Locate the TPS on the throttle body.
2. Disconnect the electrical connector.
3. Use a multimeter to check the resistance according to the service manual specifications.
4. If the TPS is faulty, replace it and reconnect the electrical connector.

5. Check Transmission Control Module (TCM)

Tools Required: OBD-II scanner, socket set.
Sub-steps:
1. Inspect the TCM for any visible damage or corrosion on the connectors.
2. Clear any fault codes using the OBD-II scanner.
3. Test drive the vehicle to see if the issue persists.