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

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

4 min read

606 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

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

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

Symptoms

•Transmission slipping during acceleration
•Unusual engine revving without corresponding vehicle speed increase
•Delayed engagement when shifting from park to drive
•Harsh or abrupt shifting between gears
•Check engine light illuminated
•Fluid leaks underneath the vehicle

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; inspect for discoloration or burnt smell.
3
Inspect the transmission fluid cooler lines for any signs of leaks or damage.
4
Conduct a visual inspection of the transmission for external leaks or signs of wear.
5
Test the vehicle's throttle position sensor (TPS) for proper operation using a multimeter.
6
Check for any signs of electrical issues, such as damaged wiring or faulty connectors to the transmission control module.

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
•Torque wrench
•Transmission fluid pump
•Funnel
•Multimeter

Parts Required

•Transmission fluid (Toyota ATF WS)
•Transmission filter and gasket (if applicable)

Related Faults

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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; inspect for discoloration or burnt smell.
3
Inspect the transmission fluid cooler lines for any signs of leaks or damage.
4
Conduct a visual inspection of the transmission for external leaks or signs of wear.
5
Test the vehicle's throttle position sensor (TPS) for proper operation using a multimeter.
6
Check for any signs of electrical issues, such as damaged wiring or faulty connectors to the transmission control module.

Solution

1. Preparation

Gather necessary tools and parts.
Ensure the vehicle is parked on a level surface and the engine is off.
Disconnect the negative battery terminal to avoid electrical shorts.

2. Check and Replace Transmission Fluid

Sub-steps:
1. Locate the transmission dipstick; remove it and wipe it clean.
2. Insert the dipstick back into the tube, remove it again, and check the fluid level.
3. If low, add the recommended transmission fluid (Toyota ATF WS).
4. If fluid is burnt or contaminated, proceed to drain and replace the fluid.
5. To drain, remove the transmission drain plug (if equipped) and allow fluid to completely drain into a pan.
6. Replace the drain plug with a new gasket, torque to manufacturer specifications (typically 7-9 ft-lbs).
7. Refill the transmission with new fluid using a funnel through the dipstick tube.

3. Inspect and Repair Transmission Components

Sub-steps:
1. Remove the transmission pan by loosening the bolts and carefully detaching it.
2. Inspect the filter for clogs and replace it if necessary.
3. Clean the transmission pan and magnet thoroughly to remove debris.
4. Reinstall the transmission pan with a new gasket, torque to manufacturer specifications (typically 10-12 ft-lbs).
5. Reconnect any electrical connectors that were removed during inspection.

4. Test Drive and Recheck Fluid Levels

Sub-steps:
1. Reconnect the negative battery terminal.
2. Start the engine and let it idle for a few minutes.
3. Shift through each gear to ensure smooth operation.
4. Take the vehicle for a test drive, checking for slipping issues.
5. After the test drive, check the transmission fluid level again and top off if necessary.