Torque Converter Clutch Pulse Width Modulation Solenoid Valve
The TCC PWM solenoid valve is a normally closed (hydraulically), pulse width modulation (PWM) solenoid which is used to control the apply and release of the converter clutch. The control module operates the solenoid with a negative duty cycle at a fixed frequency of 32 Hz in order to control the rate of TCC apply/release. The solenoid's ability to ramp the TCC apply and release pressures results in smoother TCC operation.
When the vehicle's operating conditions are appropriate to apply the TCC, the control module immediately increases the duty cycle to approximately 22 percent. The control module then ramps the duty cycle up to a maximum of 98 percent in order to achieve full TCC apply pressure. The rate at which the control module increases the duty cycle controls the TCC apply. Similarly, the control module also ramps down the TCC solenoid duty cycle in order to control TCC release.
Some operating conditions prevent or enable TCC apply under various conditions. Refer to Automatic Transmission Fluid Temperature Sensor in this section. Also, if the control module receives a zero voltage signal from the TCC brake switch, signaling that the brake pedal has been depressed, the control module immediately releases the TCC.
TCC duty cycle for ECCC equipped vehicles is 22 percent for minimum apply pressure and 43 percent for maximum apply pressure. The TCC PWM solenoid valve will typically be 40-60 percent at full apply. Your results may vary.
The TCC PWM solenoid valve resistance should measure 10-12 ohms when measured at 20°C (68°F) and 13-15 ohms when measured at 88°C (190°F).