Skylark V6-191 3.1L VIN M SFI (1994)
Torque Converter Clutch Solenoid: Description and Operation
Torque Converter Clutch Solenoid
Transmission Control Wiring.
The purpose of the Transmission Converter Clutch (TCC) feature is to eliminate the power loss of the torque converter stage when the vehicle is in a
cruise mode. The TCC system uses a solenoid operated valve to couple the engine flywheel to the input shaft of the transmission 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 and allows
the converter clutch to apply.
A second solenoid, the PWM (Pulse Width Modulator) solenoid is used to regulate the fluid pressure to the torque converter clutch to "cushion" the
apply of the clutch. The PCM controls the TCC apply solenoid by looking at several sensors.
^
Engine must be in closed loop operation.
^
Vehicle Speed Sensor (VSS). Speed must be above a certain value before the clutch can apply.
^
Engine Coolant Temperature (ECT). Engine must be warmed up before the clutch can apply.
^
The 4T60-E transaxle uses two solenoids for shifting. Based on N/V ratio (engine speed vs vehicle speed) the PCM knows which gear the
transaxle is operating in. The PCM uses this information to vary the conditions under which the TCC applies and releases.
^
Throttle Position (TP) Sensor. After the converter clutch applies, the PCM uses the information from the TP sensor to release the clutch when
the car is accelerating or decelerating at a certain rate.
^
Another switch used in the TCC circuit is a brake switch which opens the 12 volt supply to the TCC solenoid when the brake is depressed.
