Possible reasons for increased automatic transmission speed when switching:
* Damaged Throttle Position Sensor (TPS): Incorrect data sent by the TPS can cause improper timing between the engine and automatic transmission, resulting in higher RPM.
* Faulty speed sensor: The speed sensor provides the automatic transmission with information about the vehicle’s speed. If the sensor is faulty, the automatic transmission may shift into a lower gear at higher speeds, resulting in higher rpm.
*Wiring problems: Opens or shorts in the wiring can disrupt communication between the automatic transmission and the transmission control module (TCM).
* Faulty TCM: The TCM controls the operation of the automatic transmission and can cause increased RPM if it is faulty.
*Low Transmission Fluid Level: Low transmission fluid level can cause loss of pressure and shift slippage. This can cause increased rpm as the transmission tries to compensate for the loss of pressure.
* Dirty Transmission Filter: A dirty transmission filter can restrict the flow of transmission fluid, which also results in increased RPM.
* Worn or damaged clutches: Clutches in automatic transmissions can become worn or damaged over time, resulting in slippage and increased RPM.
* Hydraulic system malfunction: The automatic transmission’s hydraulic system is responsible for shifting gears. A malfunction in this system can lead to increased speed.
Diagnostics:
To diagnose a problem with high automatic transmission speeds, a mechanic will usually perform the following steps:
* Scan fault codes
* Checking the level and condition of the transmission fluid
* Checking sensors and wiring
* Test drive with connected diagnostic equipment
* Automatic transmission overhaul (in extreme cases, if other repair methods have failed)
Repair:
Depending on the cause of the problem, repairs may include replacing faulty sensors, wiring repairs, TCM replacement, transmission service (fluid change, filter flush), or automatic transmission rebuild.