Why will my Toyota Highlander not turn on?

If your Toyota Highlander won't start, there could be several potential causes. The most common reasons include a dead battery, a problem with the alternator, or an issue with the electrical system. Let's explore these possibilities in more detail.

Checking the Battery

The first thing to check is the battery. A dead or dying battery is one of the most frequent reasons a Toyota Highlander won't turn on. Try jump-starting the vehicle or testing the battery with a voltmeter. If the battery is low or not holding a charge, it will need to be replaced.

Inspecting the Alternator

Another common culprit is a faulty alternator. The alternator is responsible for charging the battery while the engine is running. If the alternator is not working properly, it can prevent the battery from maintaining a sufficient charge, causing the vehicle to not start. Have a mechanic test the alternator to determine if it needs to be repaired or replaced.

Troubleshooting Electrical Issues

In some cases, the issue may be related to the vehicle's electrical system. This could include problems with the starter, wiring, or other electrical components. If the battery and alternator check out, the next step would be to have a mechanic perform a comprehensive electrical system diagnosis to identify and address any underlying electrical problems.

Other Potential Causes

While less common, other factors that could prevent a Toyota Highlander from starting include:

• Fuel system issues, such as a clogged fuel filter or faulty fuel pump


• Engine problems, like a failed ignition coil or spark plugs


• Security system malfunctions, which can disable the engine from starting

If you've ruled out the battery, alternator, and basic electrical components, these other potential causes may need to be investigated by a qualified automotive technician.

In summary, the most likely reasons a Toyota Highlander won't turn on are a dead battery, a faulty alternator, or an electrical system problem. By systematically troubleshooting these common issues, you can often identify and resolve the underlying cause, getting your Highlander back on the road.

What is the most common problem with a Toyota Highlander?

The most common problem with the Toyota Highlander is a major oil leak and loss of oil pressure caused by a faulty VVT-i oil line. Other frequent issues include infrequent but noticeable interior rattles, especially from the moonroof or dashboard, and problems with the 8-speed automatic transmission in 2017-2019 models, leading to noises, delayed shifting, and failure. 
You can watch this video to learn about common problems with Toyota Highlander, including the 8-speed transmission issue: 59sChris DrivesYouTube · Jul 5, 2025
Most common problems

• VVT-i oil line rupture: This is the most frequent and serious issue, where the oil line bursts, causing a massive oil leak that can lead to complete engine failure if the vehicle is driven while the low oil pressure light is on. A revised part has been issued, but it has also been reported to have the same problem. 
• Interior rattles and noises: Many owners report various rattles and squeaks coming from the interior, such as the moonroof, dashboard, or infotainment screen, particularly on bumpy roads or in cold weather. 
• 8-speed automatic transmission: Specific models, particularly the 2017–2019 Highlanders, have been associated with issues such as a whining noise, delayed shifts, hard shifts, and even complete failure. 
• Airbag sensor failure: Some models have a faulty front passenger airbag sensor that can short-circuit, preventing the airbag from deploying correctly. 

Other potential issues

• Air and water leaks: Some model years have reported issues with plugged sunroof drain lines, leading to water leaks inside the vehicle. 
• Check engine light: This can be caused by various issues, such as the hose coming off the air filter housing or a failed oxygen sensor. 
• Brake issues: Some models have reported premature wear of brake pads and rotors, or a vibrating sensation when braking. 

This video discusses problems with the 8-speed transmission in the 2017-2019 Toyota Highlander: 58sThe Car Care NutYouTube · Jul 31, 2021

What does it mean when my car has power but won't start?

A car with power but no start is likely caused by a faulty starter motor, a bad ignition switch, or a problem with the car's electrical connections. Other common culprits include a blown fuse or relay, a loose or corroded battery cable, a problem with the fuel pump, or a malfunctioning shift safety switch. 
Electrical and connection issues

• Faulty starter motor: If you hear a single click when you turn the key but the engine doesn't crank, a bad starter is a likely cause. 
• Bad ignition switch: This switch sends power to the starter. If it's faulty, accessories might work, but the engine won't crank. 
• Loose or corroded battery terminals: Even with a charged battery, corrosion or loose connections can prevent the flow of power needed to start the engine. 
• Blown fuse or faulty relay: A blown fuse or bad relay in the starter circuit can prevent power from reaching the starter. 
• Key fob battery (for push-button start): A dead or weak key fob battery can prevent a modern car from recognizing the key and starting. 

This video explains how to check for common causes like a faulty starter or a bad key fob battery: 55sFixITYouTube · Jan 23, 2025
Mechanical and safety issues

• Faulty neutral safety switch: In an automatic car, this switch prevents starting unless the gear selector is in Park or Neutral. Wiggling the shifter while trying to start can sometimes temporarily fix this. 
• Fuel system problems: If the engine cranks but won't "catch," a problem with the fuel pump or a clogged fuel filter could be the issue. 
• Security system lockout: The car's anti-theft system can malfunction and prevent it from starting. 
• Bad ignition coil or spark plugs: These are necessary for the engine to ignite. If they are faulty, the engine will crank but not start. 

This video demonstrates how to check the neutral safety switch and other potential issues: 59sHonest Mechanic ColoradoYouTube · Jan 24, 2024
Troubleshooting steps

• Check battery connections: Wiggle the battery terminals to ensure they are tight and clean off any white, powdery corrosion. 
• Try a jump-start: A jump-start can help determine if the battery has enough power to crank the engine, even if it shows a good voltage reading. 
• Check fuses and relays: Locate the fuse box and visually inspect the fuses for the starter and ignition. You can also swap a suspect relay with a known-good one, like the horn relay, to test it. 
• Check the gear selector: For automatic transmissions, try shifting to Neutral or jiggling the gear shifter while in Park to see if the safety switch is the culprit. 
• Replace the key fob battery: If you have a push-button start, try replacing the battery in your key fob. 

Why does my Toyota have power but won't start?

Ignition System Problems
If the ignition switch, ignition coil, or key fob is malfunctioning, your Toyota may not start. A faulty ignition switch can prevent the car from turning on, while issues with the ignition coil could stop the engine from firing properly.

Why is my Toyota Highlander not turning on?

A Toyota Highlander may not turn on due to a dead or weak battery, a faulty starter, or issues with the fuel or ignition systems. Other common causes include a loose battery terminal connection, a blown fuse, a bad key fob battery, or a problem with the anti-theft immobilizer system. 
Electrical and starting system issues

• Dead battery: This is the most common cause. Check if the dashboard lights turn on dimly or if there is a clicking sound when you try to start the car. A voltmeter can check the battery's voltage, and a jump-start can be a temporary solution. 
• Corroded or loose battery terminals: Clean the battery terminals and ensure the cables are tightly secured to the battery posts. 
• Faulty starter or starter relay: A faulty starter or relay can prevent the engine from turning over. A clicking sound often points to the starter relay, while a lack of sound might indicate a faulty starter motor or a completely dead battery. 
• Blown fuses: Check the fuse box for any blown fuses, especially the main fuse, as this can cut all power. 
• Bad alternator: If the alternator isn't charging the battery while the engine is running, the battery will eventually die. 

Key and security system issues

• Dead key fob battery: If you have a push-button start, a dead fob battery will prevent the car from starting. You may see a "key not detected" message. To start, press the fob directly against the start/stop button. 
• Immobilizer system: The car's security system can prevent it from starting if it doesn't recognize the key or if there's a malfunction. 

Fuel and ignition system issues

• No fuel: While simple, ensure there is enough gas in the tank. 
• Faulty fuel pump or clogged fuel filter: These can prevent the engine from getting the fuel it needs to start. 
• Ignition system problems: Issues with spark plugs or ignition coils can prevent the engine from firing. 

Other potential issues

• Steering wheel lock: If the steering wheel is locked, it can prevent the ignition from turning. Try to gently turn the wheel while turning the key. 
• Neutral safety switch: The shift lever must be in Park or Neutral for the engine to start. If the neutral safety switch is faulty, it can prevent the car from starting. 

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