Torque Converter Clutch Pulse Width Modulation Solenoid Valve

The Torque Converter Clutch Pulse Width Modulation (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. See Figure or Figure . The PCM operates the solenoid with a negative duty cycle at a fixed frequency of 32 Hz 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 PCM immediately increases the duty cycle to approximately 22 percent. The PCM then ramps the duty cycle up to a maximum of 98 percent to achieve full TCC apply pressure. The rate at which the PCM increases the duty cycle controls the TCC apply. Similarly, the PCM 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. Also, if the PCM receives a zero voltage signal from the TCC brake switch, signaling that the brake pedal has been depressed, the PCM immediately releases the TCC.

TCC duty cycle for Electronically Controlled Capacity Clutch (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 68°F (20°C) and 13-15 ohms when measured at 190°F (88°C).