Automatic Transmission - Introduction & Repair Instructions: Specifications Saturn ION I

Transmission Fluid Temperature (TFT) Sensor Specifications

Transmission Fluid Temperature (TFT) Sensor Specifications

Fastener Tightening Specifications

Fastener Tightening Specifications

Transmission General Specifications

Transmission General Specifications

Fluid Capacity Specifications

Fluid Capacity Specifications (4T40-E)

End Play Specifications

End Play Specifications (Selective Washer Table)

Clutch Plate Selection Specifications

Direct Clutch Plate Selection Specifications

Reverse Clutch Backing Plate Specifications

Torque Converter Assembly Removal

1. Remove the torque converter assembly (55).
2. Remove the turbine shaft O-ring (41) from the end of the turbine shaft.

Torque Signal Regulating Valve

The torque signal regulating valve regulates the line pressure into the torque signal fluid circuit. Filtered actuator feed fluid pressure from the PCS controls this regulation. Torque signal fluid pressure is routed to the accumulator valves and to the boost valve in order to control shift feel.

Torque Converter/Cooler and Lube Circuits

Refer to reverse range for a complete description of these circuits.

Scheme 1

Torque Converter

Release fluid pressure is routed to the torque converter in order to keep the TCC released. Fluid leaves the converter in the apply fluid circuit.

Torque Converter Clutch

With the TCC control solenoid valve Off, the converter clutch is released in Second gear.

Overdrive Range, Third Gear - Torque Converter Clutch (TCC) Not Applied (W/o Electronic Range Select Mode)

As vehicle speed increases and operating conditions become appropriate, the PCM energized the 2-3 shift solenoid valve in order to shift the transmission into Third gear. The manual valve remains in the Overdrive (D) position, and line pressure continues to feed the drive and the PRND4 fluid circuits.

Torque Converter Clutch (TCC)

Torque Converter Clutch (TCC) Under normal operating conditions the TCC is released in Third gear. However the TCC apply could vary depending upon the vehicle application, and the TCC may be calibrated in order to apply in Overdrive Range - Third gear.

Overdrive Range, Fourth Gear - Torque Converter Clutch (TCC) Applied (W/o Electronic Range Select Mode)

When operating conditions are appropriate, the PCM energizes the 1-2 shift solenoid valve in order to shift the transmission into Fourth gear. In addition, the TCC is applied in Fourth gear. The manual valve remains in the Overdrive position and line pressure continues to feed the Drive and the PRND4 fluid circuits.

Apply fluid is routed to the torque converter at the same time that release fluid exhausts from the converter. Apply fluid pressure applies the TCC.

Overdrive Range, 4-3 Downshift - Torque Converter Clutch (TCC) Not Applied (W/o Electronic Range Select Mode)

When the transmission is operating in Overdrive Range - Fourth Gear, a forced 4-3 downshift will occur following a significant increase in throttle position. At minimum throttle, vehicle speed will decrease gradually (coastdown) and the PCM will command a 4-3 downshift. The PCM will also initiate a 4-3 downshift if the engine load is increased while the throttle position remains the same (for example, driving up a steep hill).

The PCM commands TCC release prior to initiating a 4-3 downshift. When the TCC is in the release position, release fluid pressure is routed to the pressure switch assembly. This fluid pressure signals the PCM that the TCC is in the release position. The TCC is not applied under normal operating conditions in Third gear.

Scheme 2

The PCM will release the TCC before downshifting into Manual Second. The TCC will not reapply in Second gear under normal operating conditions.

Scheme 3

Torque Converter Clutch Pulse Width Modulated Solenoid Valve

The torque converter clutch (TCC) solenoid valve is a normally closed, pulse width modulated (PWM) solenoid used to control the apply and release of the converter clutch. The TCM operates the solenoid with a negative duty cycle at a fixed frequency of 42 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 vehicle operating conditions are appropriate to apply the TCC, the TCM immediately increases the duty cycle to approximately 42 percent. The TCM then ramps the duty cycle up to approximately 90 percent to achieve full TCC apply pressure. The rate at which the TCM increases the duty cycle controls the TCC apply. Similarly, the TCM also ramps down the TCC solenoid duty cycle to control the TCC release.

Some operating conditions prevent or enable the TCC apply under various conditions. Also if the TCM receives a high voltage signal from the brake switch, indicating that the brake pedal is depressed, the TCM immediately releases the TCC.

Note that the duty cycles in the graph are for example only. Actual duty cycles vary depending on the vehicle application and the vehicle operating conditions.

The TCC solenoid valve resistance should measure between 10-11 ohms when measured at 20°C (68°F). The resistance would measure approximately 16 ohms at 150°C (300°F).

Scheme 4