how to troubleshoot the AWD system in my Toyota Highlander Third Generation (2014-2019)

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

3 min read

526 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 troubleshoot and fix AWD issues in the 2014-2019 Toyota Highlander. Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

Affected Component

Electrical

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow vehicle components to cool down before inspecting or touching.

Symptoms

•AWD warning light illuminated on the dashboard
•Vehicle unable to engage AWD mode
•Unusual noises from the drivetrain
•Slipping or loss of traction on slippery surfaces
•Increased tire wear
•Vibrations during acceleration

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to check for AWD-related fault codes.
2
Inspect the AWD system's fuses and relays for any signs of damage or failure.
3
Check the fluid level and condition in the rear differential and transfer case.
4
Visually inspect the AWD components, including the transfer case, driveshaft, and rear differential for leaks or damage.
5
Test the operation of the AWD actuator and related sensors for functionality.
6
Verify the condition of the tires, ensuring they are properly inflated and have even tread wear.

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
•Fuse puller
•Fluid pump

Parts Required

•Replacement fuses (if necessary)
•Gear oil (75W-90)
•AWD actuator (if needed)

Related Faults

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to check for AWD-related fault codes.
2
Inspect the AWD system's fuses and relays for any signs of damage or failure.
3
Check the fluid level and condition in the rear differential and transfer case.
4
Visually inspect the AWD components, including the transfer case, driveshaft, and rear differential for leaks or damage.
5
Test the operation of the AWD actuator and related sensors for functionality.
6
Verify the condition of the tires, ensuring they are properly inflated and have even tread wear.

Solution

1. Preparation

Gather all necessary tools and parts.
Ensure the vehicle is parked on a flat surface and the parking brake is engaged.
Disconnect the battery to prevent any electrical shorts.

2. Inspect and Replace Fuses

Locate the fuse box under the dashboard or in the engine compartment.
Use a fuse puller to remove and inspect the AWD fuses.
Replace any blown fuses with the appropriate amperage rated fuse.

3. Check and Change Fluids

Remove the fill plug from the rear differential and transfer case.
Check fluid levels; if low, top off with manufacturer-recommended fluid (typically 75W-90 gear oil).
If the fluid is dirty or smells burnt, drain and replace it with fresh fluid.

4. Inspect and Repair Components

Examine the driveshaft and CV joints for any signs of wear or damage.
If any components are damaged, replace them using:
- A socket set for removing bolts
- Torque wrench to ensure proper torque specifications are met during reassembly.

5. Test the AWD Actuator

Reconnect the battery and start the vehicle.
Engage the AWD system (if applicable) and listen for the actuator engagement noise.
If there are issues, replace the actuator as per manufacturer specifications.