Electronic Transmission

The 4T65-E is a fully automatic front wheel drive electronically controlled transmission. The 4T65-E provides four forward ranges including overdrive. The PCM controls shift points by means of two shift solenoids. A vane-type oil pump supplies the oil pressure. The PCM regulates oil pressure by means of a pressure control solenoid valve. All vehicles equipped with a 4T65-E transmission have an Electronically Controlled Capacity Clutch (ECCC) system. In the ECCC system, the pressure plate does not fully lock to the torque converter cover. It is instead precisely controlled to maintain a small amount of slippage between the engine and the turbine, reducing driveline torsional disturbances.

• 1-2 & 2-3 Shift Solenoid
  
  The shift solenoid valves are two identical, normally open, electronic exhaust valves that control upshifts and downshifts in all forward gear ranges. These shift solenoid valves work together in a combination of ON and OFF sequences to control the positions of the 1-2 and 2-3 shift valve trains. The PCM monitors numerous inputs to determine the appropriate solenoid state combination and the transmission gear for the vehicle operating conditions. See SHIFT SOLENOID VALVE OPERATION  table.

  The PCM energizes the shift solenoids by providing a ground to the solenoid's electrical circuit. This sends a current through the coil winding of the solenoid, thereby creating a magnetic field. The magnetic field repels the plunger inside the solenoid. This seats the solenoid metering ball against the fluid inlet port. This action prevents the exhaust of fluid through the solenoid and provides an increase in fluid pressure at the end of the shift valves. This fluid pressure initiates an upshift by moving the shift valves.

  Shift solenoid resistance should measure between 19-24 ohms when measured at 68°F (20°C) and between 24-31 ohms when measured at 190°F (88°C). The shift solenoid valves should energize when the voltage is greater than 7.5 volts. The shift solenoid valves should de-energize when the voltage is less than one volt.

• Pressure Control Solenoid
  
  The Pressure Control (PC) solenoid valve is a precision electronic pressure regulator that controls transmission line pressure based on current flow through its coil windings. As current flow is increased, the magnetic field which is produced by the coil moves the solenoid's plunger further away from the exhaust port. Opening the exhaust port decreases the output fluid pressure, which is regulated by the PC solenoid valve. This ultimately decreases line pressure. The PCM controls the PC solenoid valve based upon various inputs including throttle position, fluid temperature, MAP sensor, and gear state.

  The PCM controls the PC solenoid valve on a positive duty cycle at a fixed frequency of 585 Hz (cycles per second). Duty cycle is defined as the percentage of time when current flows through the solenoid coil during each cycle. A higher duty cycle provides a greater current flow through the solenoid. The high (positive) side of the PC solenoid valve electrical circuit at the PCM controls the PC solenoid valve operation. The PCM provides a ground path for the circuit, monitors average current, and continuously varies the PC solenoid valve duty cycle to maintain the correct average current flowing through the PC solenoid valve. The PC solenoid valve resistance should measure between 3-5 ohms when measured at 68°F (20°C).