why is my Toyota Highlander Third Generation (2014-2019) auto start-stop feature not working?

Toyota Highlander Third Generation (2014-2019)

Error Codes

1-3 hours

Time

medium

Difficulty

medium

Severity

3 min read

543 words

Problem Statement

Learn how to diagnose and fix the auto start-stop feature not working in a 2014-2019 Toyota Highlander. Step-by-step guide with diagnostic procedures and repair instructions.

Affected Component

Electrical

Estimated Time

1-3 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems
•Allow the engine to cool before inspecting the cooling system

Symptoms

•Auto start-stop feature does not engage when idling
•"Auto Start/Stop Off" indicator light is illuminated on the dashboard
•Engine continues to run when the vehicle is stopped
•Reduced fuel efficiency observed
•Potential warning messages on the display related to the engine or battery

Diagnostic Steps

1
Scan the vehicle's onboard diagnostics (OBD-II) for any error codes
2
Check the battery voltage and condition; ensure it meets the specifications for start-stop systems
3
Inspect the brake system; ensure the brake pedal is fully depressed
4
Verify the engine coolant temperature; the feature may not activate if the engine is too cold
5
Inspect the start-stop system settings in the vehicle's menu for any user-configured settings that may disable the feature
6
Check for any open recalls or service bulletins related to the auto start-stop system

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
•Multimeter
•Socket set
•Torque wrench
•Screwdrivers

Parts Required

•Replacement battery (if needed)
•Brake pedal switch (if faulty)

Related Faults

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Diagnostic Steps

1
Scan the vehicle's onboard diagnostics (OBD-II) for any error codes
2
Check the battery voltage and condition; ensure it meets the specifications for start-stop systems
3
Inspect the brake system; ensure the brake pedal is fully depressed
4
Verify the engine coolant temperature; the feature may not activate if the engine is too cold
5
Inspect the start-stop system settings in the vehicle's menu for any user-configured settings that may disable the feature
6
Check for any open recalls or service bulletins related to the auto start-stop system

Solution

1. Preparation

Gather necessary tools and parts.
Park the vehicle on a level surface and set the parking brake.
Disconnect the negative battery terminal to prevent electrical shorts.

2. Battery Inspection and Replacement

Check Battery Condition:
- Use a multimeter to measure the battery voltage; it should be above 12.4 volts.
- If the battery is below this threshold, it may need charging or replacement.
Replace Battery if Necessary:
- Remove the battery hold-down clamp with a socket set.
- Disconnect the positive terminal followed by the negative terminal.
- Remove the old battery and install the new one, connecting the positive terminal first, then the negative terminal.
- Reattach the battery hold-down clamp and ensure it is secure.

3. Brake System Inspection

Inspect Brake Pedal Sensor:
- Locate the brake pedal switch.
- Ensure it is properly aligned and functioning; if faulty, replace the switch.

4. Engine Coolant Temperature Verification

Check Coolant Temperature:
- Allow the engine to reach normal operating temperature.
- If the coolant is not reaching the required temperature, check the thermostat and replace if necessary.

5. System Reset

Reset the Start-Stop System:
- Reconnect the negative battery terminal.
- Start the vehicle and allow it to idle for a few minutes.
- Navigate to the vehicle settings and ensure the auto start-stop feature is activated.