Electronic System Description
Electronic System Description
The powertrain control module and its input/output network control the following transmission operations:
shift timing.
line pressure (shift feel).
torque converter clutch.
The transmission control is separate from the engine control strategy in the PCM, although some of the input signals are shared. When determining the best operating strategy for transmission operation, the PCM uses input information from certain engine-related and driver-demand related sensors and switches.
In addition, the PCM receives input signals from certain transmission-related sensors and switches. The PCM also uses these signals when determining transmission operating strategy.
Using all of these input signals, the PCM can determine when the time and conditions are right for a shift, or when to apply or release the torque converter clutch. It will also determine the pressure needed to optimize shift feel. To accomplish this the PCM uses three pressure control and four shift solenoids to control transmission operation.
The following provides a brief description of each of the sensors and actuators used to control transmission operation.
Turbine Shaft Speed (TSS) Sensor
The Turbine Shaft Speed (TSS) sensor is a magnetic pickup that sends the powertrain control module torque converter turbine speed information.
The TSS sensor is mounted externally on the case.
The PCM uses TSS information to help determine appropriate operating pressures and Torque Converter Clutch (TCC) operation.
Output Shaft Speed (OSS) Sensor
The Output Shaft Speed (OSS) sensor is a magnetic pickup, located at the park gear, that sends a signal to the powertrain control module to indicate transmission output shaft speed. The OSS is used for torque converter clutch control, speed scheduling and to determine electronic pressure control.
Intermediate Shaft Speed (ISS) Sensor
The Intermediate Shaft Speed (ISS) sensor is a magnetic pickup that sends planetary sun gear speed information to the PCM. The ISS is mounted externally on the center of the case.
The PCM uses the ISS information to aid in determining pressure requirements.
Transmission Fluid Temperature (TFT) Sensor
The Transmission Fluid Temperature (TFT) sensor is a thermistor-type sensor that varies a reference voltage signal. The resistance in the TFT varies with temperature. The Powertrain Control Module (PCM) monitors the voltage signal across the TFT, and uses this information to determine the transmission fluid temperature.
The TFT is located on the solenoid body.
The PCM uses the TFT signal to help determine shift scheduling, torque converter clutch operation and pressure control requirements.
It sends a voltage signal to the powertrain control module. The voltage signal varies with transmission fluid temperature. The PCM uses this signal to determine whether a cold start shift schedule is necessary. The shift schedule is compensated when the transmission fluid temperature is cold. The PCM also inhibits torque converter clutch (TCC) operation at low transmission fluid temperatures and use to determine pressure control (PC) solenoid operations.
Shift Solenoids - (SSA, SSB, SSC, SSD)
Four On/Off shift solenoids allow the powertrain control module to control shift scheduling.
The solenoids are two-way, normally open style.
The shift solenoids SSA, SSB, SSC, and SSD provide gear selection of 1st through 5th and reverse gears by directing PC pressures to the appropriate elements.
Pressure Control Solenoids (PCA, PCB, PCC)
The Pressure Control (PC) solenoids are a Variable Force Style (VFS) solenoid. The VFS type solenoid is an electro-hydraulic actuator combining a solenoid and a regulating valve.
There are three PC solenoids located in the solenoid body assembly used to control line pressure, band and clutch application pressure within the transmission.
The powertrain control module varies the current to the PC solenoid.
Torque Converter Clutch (TCC) Solenoid
The Torque Converter Clutch (TCC) solenoid is a pulse width modulating type solenoid which is used to control the apply and release of the TCC.
External Sealing
The transmission has the following parts to prevent external fluid leakage:
gaskets
lip-type seals
o-ring seals
seal rings
seal grommets
thread sealant