The Highlander uses Aisin's 6-speed automatic transmission. Founded in 1969, Aisin is a professional developer and manufacturer of automotive automatic transmissions. The Highlander is equipped with the A25D engine, which has a displacement of 2487 (mL) or 2.5 (L), a maximum power of 141 (kW) at 6000 (rpm), and a maximum torque of 238 (N·m) at 4200-4600 (rpm). A transmission is a mechanism used to change the speed and torque from the engine. It can fix or change the gear ratio between the output shaft and the input shaft, hence it is also called a gearbox. The gearbox is a very important component in a vehicle, as it can change the gear ratio and expand the torque and speed of the drive wheels. With the development of modern technology, transmissions have also been upgraded, from the original manual transmissions to today's continuously variable transmissions, and from non-synchronized to synchronized transmissions, making operation increasingly convenient. Transmissions can be classified by their operation methods as follows: Forced operation transmission: The driver directly operates the gear lever to shift gears; Automatic operation transmission: The selection of gear ratio and shifting are done automatically. The driver only needs to operate the accelerator pedal, and the transmission can control the actuators based on the engine load signal and vehicle speed signal to achieve gear changes; Semi-automatic operation transmission: Can be divided into two types, one is partial automatic shifting and partial manual (forced) shifting; the other is pre-selecting gears with buttons, and the actuator shifts gears automatically when the clutch pedal is pressed or the accelerator pedal is released. For the Highlander's transmission, the following points should be noted in daily use: Do not delay changing the transmission oil for too long. Prolonged failure to change the transmission oil can damage internal components such as bearings and the housing; Avoid coasting in neutral for extended periods. Many drivers of manual transmission vehicles coast in neutral, but for automatic transmission vehicles, coasting in neutral can cause the transmission to overheat and produce a certain impact when shifting back into D gear; Never shift into D/R gear before the vehicle has come to a complete stop. Many drivers shift directly into reverse gear before the vehicle has fully stopped, which can cause significant damage to the transmission gears and, over time, lead to gear grinding and other faults; Do not frequently climb steep slopes in D gear. When facing steep slopes, automatic transmission vehicles often overheat due to high loads or shift up too early, resulting in insufficient climbing power. In such cases, manual mode can be used to limit low gears or sport mode to protect the transmission; Do not tow the vehicle over long distances. When an automatic transmission vehicle breaks down, a flatbed tow truck should be used to move the vehicle onto the tow platform with the transmission in N gear, rather than using a tow rope or directly towing the vehicle.
