A torque converter clutch is a friction lined disk that locks the engine output to the transmission input shaft, achieving a 1:1 ratio where all of the power from the engine is reaching the transmission, and thus the drive wheels. Modern vehicles use this lockup function in nearly all of the gears to achieve better fuel economy.
What Transmission Do I Have?
In order to operate the torque converter clutch, pressurized hydraulic fluid/transmission fluid is needed. This is supplied by the torque converter clutch solenoid, which is controlled by the transmission control module/TCM or ECU/engine control unit, depending on the vehicle. When the computer wants to activate or deactivate the torque converter clutch, it sends an electrical charge to the TCC solenoid, which then causes the plunger mechanism inside to either open or close.
Symptoms of a bad TCC solenoid
Failure in the open position
When a torque converter clutch solenoid fails in the open position, the torque converter clutch will not be able to achieve lockup. This will result in more fuel consumption and increased internal heat that can cause serious damage to other components.
Symptoms of a bad TCC solenoid
Failure in the closed position
When a torque converter clutch solenoid fails in the closed position, it means that the torque converter clutch will be engaged at all times. This will cause the engine to stall when the vehicle comes to a stop.
What Transmission Do I Have?
Limp mode
If there is a problem with the TCC solenoid, some vehicles are programmed to go into Limp Mode. This locks the transmission into a single forward gear, with a maximum speed of approximately 30 mph. This is designed to protect the transmission from further internal damage.
