Torque Converter Clutch Solenoid: Description and Operation

Torque Converter Clutch Solenoid:

PURPOSE
The Transmission Converter Clutch (TCC) feature eliminates the power loss of the torque converter stage when the vehicle is in a cruise mode.

OPERATION
The TCC system uses a solenoid operated valve in the automatic transmission to couple the engine flexplate to the output shaft of the transaxle through the torque converter. This reduces the slippage losses in the converter, which increases fuel economy.

For the converter clutch to apply, at least two conditions must be met:
- Internal transmission fluid pressure must be correct.
- The PCM completes a ground circuit to energize the TCC solenoid in the transmission, which moves a check ball in the fluid line.

PCM control is based on the input of three sensors:
- Vehicle Speed Sensor (VSS): Speed above PROM calibrated value above 34 mph (55 km/h).
- Engine Coolant Temperature (ECT): Engine warm
- Throttle Position (TP) Sensor: accelerating or decelerating to release clutch at a calibrated rate.

PCM is also controlled by two switches:
- Brake Switch: Opens 12 volt supply when brake is depressed.
- Second Gear Switch (3T40 Transaxle): Prevents application until second gear. However, TP and VSS inputs result in TCC apply in third gear.

LOCATION
Automatic Transaxle.