my Toyota Highlander Third Generation (2014-2019) has a slipping transmission what should I check

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

3 min read

554 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 a slipping transmission in a 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

•Always allow the engine to cool before working on the transmission.
•Ensure the vehicle is securely raised on jack stands if working underneath.

Symptoms

•Transmission hesitates during shifting
•RPM increases without a corresponding increase in speed
•Engine revs high before the vehicle accelerates
•Check engine light illuminated
•Unusual noises during gear changes
•Possible fluid leaks under the vehicle

Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to check for error codes.
2
Inspect the transmission fluid level and condition; look for discoloration or a burnt smell.
3
Check for any visible leaks around the transmission and its associated components.
4
Test the transmission fluid pressure using a pressure gauge to ensure it meets specifications.
5
Examine the transmission filter for clogs or blockages if applicable.
6
Inspect the transmission control module (TCM) and wiring for faults or damage.

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
•Funnel
•Socket set for drain plug
•Torque wrench
•Screwdrivers
•Gasket scraper
•Multimeter
•Wrench set

Parts Required

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

Related Faults

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Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to check for error codes.
2
Inspect the transmission fluid level and condition; look for discoloration or a burnt smell.
3
Check for any visible leaks around the transmission and its associated components.
4
Test the transmission fluid pressure using a pressure gauge to ensure it meets specifications.
5
Examine the transmission filter for clogs or blockages if applicable.
6
Inspect the transmission control module (TCM) and wiring for faults or damage.

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 for safety.

2. Check and Replace Transmission Fluid

Sub-steps:
1. Locate the transmission dipstick and remove it.
2. Wipe it clean and reinsert it to check the fluid level.
3. If fluid is low, add the correct type of ATF (Toyota WS) until it reaches the proper level.
4. If fluid is dark or has a burnt smell, proceed to drain and replace it.
Tools Required:
- Transmission fluid pump
- Funnel
- Socket set for drain plug

3. Replace Transmission Filter (if applicable)

Sub-steps:
1. Remove the transmission pan by loosening the bolts (ensure to have a drain pan ready for fluid).
2. Remove the old filter and replace it with a new one.
3. Clean the pan and magnet (if equipped) before reinstalling.
4. Reinstall the pan with a new gasket and torque the bolts to manufacturer specifications.
Tools Required:
- Torque wrench
- Screwdrivers
- Gasket scraper

4. Inspect and Repair Transmission Components

Sub-steps:
1. Check all electrical connectors and wiring harnesses for damage and repair as necessary.
2. Inspect the transmission control module (TCM) for errors, and reprogram if needed.
3. If pressure tests indicate a problem, consider rebuilding the valve body or replacing solenoids.
Tools Required:
- Multimeter
- Wrench set