Mechanical reasons:
* Worn or damaged friction discs: Discs can wear over time, causing the transmission to slip and slap.
* Worn or damaged bands or chains: These components connect the planetary gears inside the transmission and can wear, causing slippage and knocking.
*Planetary Gear Problems: Planetary gears transmit torque from the engine to the wheels and can become worn or damaged, causing shock and slippage.
*Transmission Fluid Leaks: Low fluid levels or leaks can cause lubrication problems and cool down critical transmission components, leading to knocking and slipping.
* Contaminated Transmission Fluid: Dirt and debris in transmission fluid can clog filters and cause shifting problems, leading to knocks.
Electrical reasons:
* Faulty Solenoids: Solenoids control the flow of transmission fluid inside the transmission and can fail, resulting in rough shifting and knocking.
* Faulty Transmission Control Module (TCM): The TCM is an electronic module that controls the operation of the transmission, and a malfunction can result in improper shifting and knocking.
*Faulty Shift Position Sensors: These sensors tell the TCM the current shift position and a malfunction can result in improper shifting and bumping.
* Broken Harness: The wiring harness connects the TCM to other transmission components, and a break can result in loss of communication and improper shifting.
Software reasons:
* Incorrect TCM software: The TCM software can monitor transmission performance, and errors in the software can cause incorrect shifting and knocking.
*Outdated TCM Software: New versions of TCM software may contain updates that resolve shifting issues, and missing them may result in shocks.
Other reasons:
* Damage to the driveshaft: Damage to the driveshaft can result in vibrations and shocks that can be transmitted to the transmission.
* Torque Converter Problems: The torque converter is located between the engine and transmission and can become worn or damaged, causing slippage and knocking.
*Worn Engine or Transmission Mounts: Worn mounts can allow excessive movement of the engine or transmission, resulting in misalignment and knocking.