A humming or whining noise from the gearbox at highway speed often means low fluid, worn bearings, or a failing torque converter. Here’s what to check first and whether it’s safe to keep driving.
What's Causing That Gearbox Noise in Your Fortuner III?
If you're hearing a humming or whining sound from the transmission at highway speeds (60–80 mph / 100–130 km/h), it's usually a sign that something inside the gearbox isn't happy. In my years working on Toyota Fortuners, the most common culprits are low automatic transmission fluid (ATF) level or degraded fluid, but worn bearings or a failing torque converter can also make that noise. Let's break it down.
