Toyota Highlander Ignition Coil Problems

The Toyota Highlander is a popular choice among SUV enthusiasts for its reliability and performance. However, even the most well-engineered vehicles can experience issues, and one common problem that has plagued some Highlander owners is related to the ignition coils.

Day by day, the number of affected owners is increasing. Therefore, we have come up to explore Toyota Highlander ignition coil problems, exploring how these malfunctions manifest themselves in day-to-day driving, potential causes for their occurrence, and possible solutions. 

Whether you’re a current owner experiencing symptoms related to ignition coil problems or simply interested in learning more about this issue, we will provide valuable insights into an often overlooked aspect of vehicle maintenance.

Toyota Highlander Ignition Coil Problems

Toyota Highlander Ignition Coil Problems

Toyota Highlander ignition coil problems can stem from a variety of causes, such as exposure to extreme temperatures, moisture buildup, or simply normal wear and tear over time. 

However, when an issue becomes repeated or widespread, faults in the internal components can also be blamed. Let’s see what users say about Toyota Highlander ignition coil issues. 

Repeated Ignition Coil Failure

Many Toyota Highlander owners complained about a recurring issue with ignition coils in 2007 models. Most of them have already replaced coils several times, trying different brands, but the ignition coil in a particular cylinder consistently fails. 

Moving coils between cylinders didn’t resolve the issue. In such a situation, owners are wondering if there’s an underlying issue causing the repeated failures. The plug could be shorting/opening to cause excessive voltage, or the coil driver circuit from ECM could be staying on too long, causing excess current.

Besides, improper grounding may cause voltage spikes that harm the ignition coils, potentially leading to issues for Toyota Highlander owners. To address this, it is recommended to conduct a thorough electrical inspection. If the spark plug is in good condition, checking the driver circuit on and off time with a noid light or scope can be helpful. 

If no misfire is present, intermittent problems are likely. Wiggle testing the wiring at the problematic cylinder’s coil and along the wiring harness to the ECM can help identify issues. Repairing any wiring problems, poor connections at the coil connector, or misrouted/chafing harnesses is important. 

Related: Should I Replace Ignition Coils With Spark Plugs?

Jerking and Trembling While Accelerating

Ignition coil issues in 2017 Highlander Hybrid models have been troubling numerous owners. They experienced jerking and trembling while accelerating, with the dealer diagnosing a misfiring ignition coil. The coil was replaced, but the issue recurred. They are concerned about whether all coils and spark plugs should be replaced.

A failing coil can cause a spark plug to foul with build-up. This can lead to weak spark generation, overloading the new coil, and eventual coil failure. Although individually malfunctioning ignition coils can be replaced as needed if one coil fails in close succession to another, it may indicate an underlying systemic issue within the ignition system.

Misfiring Cylinder #3 and #4

Toyota Highlander owners frequently experience engine misfiring issues, particularly related to cylinders 3 and 4 as indicated by OBD II scanner reports. The primary cause of misfiring is often traced back to ignition problems, specifically with the spark plug or ignition coil. 

If the spark plug is functioning properly, it indicates potential issues with the ignition coil. To troubleshoot, if there is no frequency signal from the PCM on the ignition coil driver circuit or if there is no visible pattern on a scope, disconnect the coil and check for DC voltage on the driver circuit at the ignition coil connector. 

Any significant voltage on that wire suggests a short circuit elsewhere, which should be located and repaired. If there is no voltage on the driver circuit, turn off the ignition, disconnect the PCM connector, and check for continuity of the driver between the PCM and the coil. 

If there is no continuity, repair any open or short circuits to the ground in the circuit. However, if continuity exists, proceed to check for resistance between the ground and the ignition coil connector; infinite resistance should be present. If not, repair any short circuits to ground in the coil driver circuit. 

Note: If there are no open or shorted wires and no trigger signal to the coil, consider a faulty PCM coil driver as a potential cause.

How to Fix Ignition Toyota Highlander Coil Problems

In contrast to numerous other parts in your Toyota Highlander, ignition coils cannot be repaired and must be replaced to resolve any issues. However, it is essential to first identify the faulty ignition coil before proceeding with the testing and replacement process, which we will outline sequentially below.

Testing the Ignition Coil

Start by disconnecting the negative terminal of the battery to ensure safety. Next, locate the ignition coil, which is typically found near the engine’s cylinder head. Using a digital multimeter set to ohms, measure the resistance of the coil’s primary and secondary windings.

For the primary winding, you should typically see a resistance reading between 0.4 to 2 ohms, while for the secondary winding, it should fall between 8,000 to 11,500 ohms. Ensure that there are no significant deviations from these values, as it may indicate a faulty ignition coil.

Next, connect the spark tester to the ignition coil and ground it to the engine block. Crank the engine while observing whether a strong, blue spark is present at the tester’s gap. If no spark is detected, check for any loose connections or damaged components that could be impeding proper operation.

Additionally, inspect the external condition of the ignition coil for any signs of physical damage or corrosion. A visual examination can often reveal cracks or carbon tracking that might affect its performance.

After completing these steps, reconnect the battery and start the vehicle to check for any improvement in engine performance or smoothness in operation.

Replacing the Ignition Coil

Replacing the ignition coil in a Toyota Highlander entails several steps to ensure successful installation. Start by disconnecting the negative battery terminal to prevent any electrical mishaps during the process. 

Then, locate and access the ignition coil unit, which typically involves removing the engine cover for easy access. Next, carefully detach the electrical connectors and the mounting bolts securing the ignition coil in place.

After removing the old ignition coil, inspect the area for any debris or damage that may need attention before installing the new one. Ensure that the replacement ignition coil matches the specifications of your Toyota Highlander model. 

Once ready, position and secure the new ignition coil using its mounting bolts and reconnect all necessary electrical connections. Reinstall any components previously removed, such as the engine cover, and secure them back into place. 

Finally, reattach the negative battery terminal and test start your vehicle to confirm that the replacement was successful. As always, refer to your vehicle’s specific manual for detailed instructions and safety precautions during this process.

Final Words

Toyota Highlander ignition coil problems present a significant issue for owners of this popular SUV. The frequent occurrence of ignition coil failure can lead to a range of performance issues, from rough idling to stalling and difficulty starting the vehicle. 

While Toyota has made efforts to address these problems through recalls and improved design, Highlander owners need to remain vigilant and proactive in maintaining their vehicles. Regular inspection and timely replacement of ignition coils can help mitigate the risk of experiencing these issues.

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