my Toyota Highlander Third Generation (2014-2019) won't stay in gear, what should I check?

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

3 min read

582 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 issues in the 2014-2019 Toyota Highlander. 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 checking transmission fluid levels.

Symptoms

•Transmission slips out of gear unexpectedly
•Check engine light illuminated
•Delayed or harsh shifting when changing gears
•Grinding or unusual noises during gear engagement
•Loss of power during acceleration
•Fluid leaks under the vehicle

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify any transmission-related fault codes.
2
Check the transmission fluid level and condition; look for contamination or burnt odor.
3
Inspect the transmission fluid lines for leaks or damage.
4
Verify the operation of the transmission control module (TCM) by checking electrical connections and harnesses.
5
Conduct a visual inspection of the shift linkage and cables for any signs of wear or misalignment.
6
Test drive the vehicle to replicate the issue under controlled conditions.

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
•Multimeter
•Socket set
•Torque wrench
•Pliers
•Funnel

Parts Required

•Toyota ATF WS transmission fluid
•Shift linkage bushings (if worn)

Related Faults

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify any transmission-related fault codes.
2
Check the transmission fluid level and condition; look for contamination or burnt odor.
3
Inspect the transmission fluid lines for leaks or damage.
4
Verify the operation of the transmission control module (TCM) by checking electrical connections and harnesses.
5
Conduct a visual inspection of the shift linkage and cables for any signs of wear or misalignment.
6
Test drive the vehicle to replicate the issue under controlled conditions.

Solution

1. Preparation

Gather necessary tools and parts.
Ensure the vehicle is parked on a level 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 and remove it.
2. Using a transmission fluid pump, extract old transmission fluid from the dipstick tube.
3. Inspect the old fluid for contaminants or burnt smell.
4. Refill the transmission with the appropriate type of fluid (recommended: Toyota ATF WS) using a funnel.
5. Start the engine and let it run for a few minutes, then check fluid level with the dipstick; add fluid as necessary to reach the proper level.

3. Inspect and Repair Electrical Connections

Tools Required: Multimeter, wire stripper, electrical tape
Sub-steps:
1. Check the TCM connectors for corrosion or damage.
2. Use a multimeter to test for proper voltage and ground at the TCM.
3. Repair any damaged wires or connectors as needed.
4. Ensure all connections are secure and free from moisture.

4. Examine the Shift Linkage

Tools Required: Socket set, pliers
Sub-steps:
1. Locate the shift linkage and check for proper alignment.
2. Tighten any loose bolts and adjust the linkage if misaligned.
3. Replace any worn or damaged bushings in the shift linkage.

5. Reconnect Battery and Test Drive

Reconnect the battery once all repairs are completed.
Test drive the vehicle to verify that the transmission stays in gear under various driving conditions.