my Toyota Highlander Third Generation (2014-2019) transmission is slipping when accelerating, what s...

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

3 min read

537 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 a 2014-2019 Toyota Highlander. Step-by-step guide with symptoms, diagnostics, and repair instructions.

Affected Component

Transmission

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Allow the engine to cool before working on the transmission.
•Disconnect the battery before performing electrical work on the TCM.

Symptoms

•Transmission slipping during acceleration
•Delayed or rough shifting between gears
•Increased engine RPM without corresponding vehicle speed increase
•Check engine light illuminated
•Unusual noises from the transmission area (grinding or whining)

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; look for discoloration or burnt smell.
3
Inspect the transmission fluid for contamination (metal shavings, debris).
4
Test the transmission fluid pressure using a pressure gauge.
5
Check for any visible leaks around the transmission seals and gaskets.
6
Inspect the transmission control module (TCM) for proper operation and connections.

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 pressure gauge
•Fluid flush machine (if applicable)
•Funnel

Parts Required

•Transmission fluid (specific type per manufacturer’s recommendation)
•Transmission filter
•Gasket or sealant (for transmission pan, 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; look for discoloration or burnt smell.
3
Inspect the transmission fluid for contamination (metal shavings, debris).
4
Test the transmission fluid pressure using a pressure gauge.
5
Check for any visible leaks around the transmission seals and gaskets.
6
Inspect the transmission control module (TCM) for proper operation and connections.

Solution

1. Preparation

Gather necessary tools and parts.
Ensure the vehicle is parked on a level surface and the parking brake is engaged.

2. Check and Replace Transmission Fluid

Drain Fluid:
- Locate the transmission drain plug; use a socket set to remove it.
- Allow fluid to completely drain into a suitable container.
Replace Transmission Filter:
- Remove the transmission pan (if applicable) by loosening bolts with a socket set.
- Carefully remove the old filter and install the new filter, ensuring proper alignment.
Refill Transmission Fluid:
- Reinstall the drain plug, tightening to the manufacturer’s specifications (consult the service manual for torque value).
- Use a funnel to refill the transmission with the correct type of ATF (consult owner’s manual for specification).

3. Perform a Transmission Fluid Flush (if needed)

Connect a Flush Machine:
- If using a flush machine, connect hoses according to the machine's instructions.
Flush Fluid:
- Follow the machine's procedure to flush out old fluid and replace it with new fluid.
Check for Leaks:
- After flushing, inspect all connections for leaks.

4. Reprogram Transmission Control Module (if applicable)

Connect OBD-II Scanner:
- Use the scanner to check for any required TCM updates or reprogramming options.
Perform Reprogramming:
- Follow the scanner prompts to reprogram the TCM if necessary.

Tools Required:

OBD-II scanner
Socket set
Torque wrench
Transmission fluid pressure gauge
Fluid flush machine (if applicable)
Funnel

Parts Required:

Transmission fluid (specific type per manufacturer’s recommendation)
Transmission filter
Gasket or sealant (for transmission pan, if applicable)

Estimated Repair Time: 2-4 hours

Safety Warnings:

Allow the engine to cool before working on the transmission.
Disconnect the battery before performing electrical work on the TCM.