my Toyota Highlander Third Generation (2014-2019) feels like it's slipping in and out of gear

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

3 min read

581 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 the 2014-2019 Toyota Highlander. 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 before working on the transmission or related components.

Symptoms

•Transmission slips or hesitates during gear shifts
•Sudden loss of power while accelerating
•Unusual noises when shifting gears (grinding or whining)
•Check engine light illuminated
•Fluid leaks under the vehicle
•Rough idle when in gear

Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner for any error codes related to the transmission.
2
Inspect the transmission fluid level and condition; check for burnt smell or dark coloration.
3
Visually examine the transmission for any visible leaks or damage to the pan or seals.
4
Check the transmission filter for blockages or contamination.
5
Test the battery voltage and health, as low voltage can affect transmission control modules.
6
Perform a road test to replicate the slipping sensation and note specific conditions when it occurs.

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
•Fluid transfer pump
•Electrical contact cleaner
•Gasket scraper

Parts Required

•Toyota ATF WS transmission fluid
•Transmission filter
•Transmission pan gasket

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Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner for any error codes related to the transmission.
2
Inspect the transmission fluid level and condition; check for burnt smell or dark coloration.
3
Visually examine the transmission for any visible leaks or damage to the pan or seals.
4
Check the transmission filter for blockages or contamination.
5
Test the battery voltage and health, as low voltage can affect transmission control modules.
6
Perform a road test to replicate the slipping sensation and note specific conditions when it occurs.

Solution

1. Preparation

Gather necessary tools and parts.
Disconnect the battery to ensure safety during repairs.
Elevate the vehicle using jack stands and secure it on a flat surface.

2. Check and Replace Transmission Fluid

Sub-steps:
- Remove the transmission dipstick and check fluid level.
- If low, add the recommended type of transmission fluid (Toyota ATF WS).
- If fluid is dirty or burnt, proceed with a fluid change.
Tools Required: Socket set, funnel, fluid transfer pump.

3. Inspect and Replace Transmission Filter

Sub-steps:
- Remove the transmission pan using a socket and ratchet.
- Clean the pan and remove the old filter.
- Install the new filter and replace the pan with a new gasket.
- Torque pan bolts to manufacturer specifications (typically around 8-10 ft-lbs).
Tools Required: Socket set, torque wrench, gasket scraper, new transmission filter, new gasket.

4. Check Transmission Control Module (TCM) Connections

Sub-steps:
- Locate the TCM, usually found near the transmission.
- Disconnect and inspect the electrical connectors for corrosion or damage.
- Clean any corrosion with electrical contact cleaner and reconnect.
Tools Required: Electrical contact cleaner, screwdriver.

5. Reconnect Battery and Test

Sub-steps:
- Reconnect the battery and clear any diagnostic trouble codes (DTCs) using the OBD-II scanner.
- Start the engine and let it reach operating temperature.
- Test drive to ensure proper shifting and verify the repair.
Tools Required: OBD-II scanner.