Possible causes of automatic transmission whining when accelerating in a Toyota:
Low transmission fluid level:
* Check the ATF fluid level. Low levels can cause insufficient lubrication and whining.
Old or contaminated transmission fluid:
* Over time, ATF fluid can degrade and lose its lubricating properties. This can result in a whining noise when changing gears.
Worn or damaged bearings:
* Worn or damaged bearings in the transmission may make a whining noise when turning.
Damaged planetary gear:
* Damaged planetary gears or sun gear may cause a howling noise when the vehicle is driven.
Transmission fluid leak:
* Leaking ATF fluid can reduce system pressure and lead to howling.
Faulty torque converter:
* The torque converter may whine if it is faulty or damaged.
Faulty Transmission Control Module (TCM):
* The TCM may not be sending the correct signals to the transmission, resulting in a whining noise.
How to diagnose and fix the problem:
* Check the transmission fluid level.
* Replace ATF fluid and filter if it is old or dirty.
* Have a qualified mechanic diagnose and repair worn or damaged bearings, planetary gear, or torque converter.
* Find transmission fluid leaks and fix them.
* Check the TCM for faults or reprogram it.
Note: Do not ignore automatic transmission whining as it can cause serious damage to the transmission and costly repairs.