Park Avenue Ultra V6-3.8L SC VIN 1 (1991)
Torque Converter Clutch Solenoid: Description and Operation
Torque Converter Clutch Solenoid
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 engage the TCC which couples 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. Another solenoid (pulse
width modulator or PWM solenoid) is used to regulate fluid pressure to the TSS to "cushion" the apply of the clutch.
For the converter clutch to apply, at least two conditions must be met.
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Internal transmission fluid pressure must be correct.
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The ECM completes a ground circuit to energize the TCC solenoid in the transmission, which moves a check ball in the fluid line.
The ECM controls the TCC apply solenoid by looking at several sensors.
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Engine must be in closed loop operation.
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Vehicle Speed Sensor (VSS). Speed must be above a certain value before the clutch can apply.
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Coolant Temperature Sensor (CTS). Engine must be warmed up before the clutch can apply.
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The 4th gear switch is used as a input to the ECM. The ECM uses the switch signal for TCC engage and disengage points.
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Throttle Position Sensor (TPS). After the converter clutch applies, the ECM uses the information from the TPS to release the clutch when the
car is accelerating or decelerating at a certain rate.
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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.
