My Toyota Highlander Has an ECM Malfunction

by Justin Cupler

The Toyota Highlander is equipped with an engine control module (ECM) that acts as the vehicle's brain. When this component fails, it can cause the engine and transmission to operate improperly, as the sensors on the engine and trannsmission can no longer communicate.


The Highlander's ECM is relatively hidden to protect it from water or inadvertent damage. Toyota mounted the ECM directly behind the vehicle's glove box compartment.


The Highlander's ECM measures about 8 inches long by 6 inches wide by 2 inches thick. Its case is made of aluminum and has several wiring harnesses plugging into it.

Master Key Registration

The Highlander requires the registration of master keys -- the key(s) with a black colored top -- to the new ECM. Insert the key in the ignition and wait for the Security light to turn on and stay on; this means the registration was successful.


The Highlander has no specified relearn procedure, as it is essentially a plug-and-play design once the dealership programs the computer. You may, however, experience mild issues while driving, such as: erratic idle, irregular shifting patterns or poor fuel economy. This is to be expected and will fade away with time.

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