Possible reasons:
Transmission problems:
*Low transmission fluid level
* Worn or damaged clutches or steel discs
* Torque converter problems
* Faulty shift valve
* Worn gears or other mechanical parts
Electrical problems:
* Faulty speed sensor
* Problems with the electronic transmission control module (TCM)
* Faulty wiring
Other possible reasons:
* Worn or damaged engine or transmission mounts
* Worn drive shafts
*Brake problems or worn brake pads
* Clogged transmission oil filter
What to do if the automatic transmission speeds up:
1. Check the transmission fluid level. If the fluid level is low, add fluid that meets the specifications in the owner’s manual.
2. Check the condition of the engine and gearbox mounts. Make sure the supports are secure and not damaged.
3. Conduct transmission diagnostics. Have the problem diagnosed by a qualified mechanic using a trouble code scanner or other diagnostic tools.
4. Check the brakes. Make sure the brakes are working properly and that the brake pads are not worn out.
5. Check the drive shafts. Inspect the drive shafts for damage or wear.
6. Replace the transmission oil filter. Regular oil filter changes can help prevent debris buildup and protect your transmission from damage.
If you cannot determine the cause yourself, it is recommended that you have the transmission repaired by an experienced mechanic.