Circuit Description

Torque Converter Clutch (TCC) solenoid valve is a Pulse Width Modulation (PWM) solenoid. When vehicle operating conditions are appropriate for TCC application, PCM begins TCC duty cycle at about 42 percent. PCM then increases duty cycle up to 90 percent, in order to achieve full TCC-apply pressure. When TCC PWM solenoid valve is de-energized, solenoid blocks filtered 2-3 drive fluid, and allows TCC signal fluid to exhaust. When energized, solenoid modulates fluid into TCC signal fluid circuit. When fully energized, modulation stops, and solenoid blocks both 2-3 drive fluid and TCC signal fluid exhaust. TCC release switch is part of Transmission Fluid Pressure (TFP) manual valve position switch. TFP manual valve position switch is mounted to transaxle valve body. TCC release switch is a normally-closed switch. Switch signals PCM that TCC is released. Torque converter release fluid pressure acts on switch contact, opening signal circuit. When circuit voltage is high, PCM recognizes TCC is no longer engaged. DTC P0742 sets when PCM detects TCC release switch is closed when TCC is commanded off.