2019 4Runner 4wd humming noise
My 2019 4Runner (113,000 miles) makes a weird humming almost grinding noise when at high speeds in 4wheel high. It is intermittent in terms of it happens every other second, almost rotational at about 50+ mph. It does this sometimes in 2w high at high speeds as well, but more noticeable in 4H.
Only happens when foot is on gas, goes away when I let off gas. Also seems to not be noticeable when pushing gas pedal hard, only when foot barely on gas.
Thinking bad U-Joint, differential, or something else. I put new rear diff fluid in a few months ago. Recently put new T-Case fluid, tranny fluid, and coolant.
In what conditions are you driving in 4wd high at high speed?