Torque Converter Clutch (TCC)
A lockup clutch inside a torque converter that mechanically locks the engine output to the transmission input at cruising speeds to improve fuel economy.
The Torque Converter Clutch (TCC) is a friction clutch mechanism located inside the torque converter housing. In standard operation, a torque converter uses fluid coupling to transfer power, which inherently allows for slippage (allowing the vehicle to idle at a stop in gear). However, this slippage wastes energy and generates heat at highway speeds.
To eliminate this energy loss, the vehicle's computer engages the TCC at cruising speeds (typically above 40 mph). When engaged, the TCC mechanically locks the engine's turbine to the transmission input shaft, creating a direct 1:1 mechanical link. This eliminates slippage, lowers transmission operating temperatures, and improves highway fuel economy.
If the TCC fails to engage, the vehicle will suffer from reduced fuel economy and the transmission may overheat. If the clutch fails to release when slowing down, the engine will shudder and stall when coming to a stop, similar to stopping a manual car without pressing the clutch. Common TCC failures include worn clutch linings, leaking hydraulic seals, or a faulty TCC control solenoid.