Transmission Control Systems: Description and Operation
DESCRIPTIONShift timing, shift feel (line pressure) and torque converter clutch control in the CD4E are controlled electronically by the powertrain control module (PCM) and its input/output network. The transaxle control is separate from the engine control strategy in the powertrain control module, although some of the input signals are shared.
Using all of these input signals, the PCM can determine when the time and conditions are right for a shift or torque converter clutch application. The PCM can also determine the line pressure needed to optimize shift feel. To accomplish these functions, the PCM controls five electronic solenoids-two on/off solenoids for shifting, one pulse-width modulate solenoid for torque converter clutch control of the torque converter clutch an electronic pressure control (EPC) solenoid for line pressure control, and a 3-2 timing/coast clutch solenoid to control the release of the coast clutch and the coordinated release of the direct clutch and the apply of the low and intermediate band, during a 3-2 downshift.
ENGINE INPUTS
Some input signals come from the engine-related sensors (mass air flow sensor (MAF sensor), engine coolant temperature sensor (ECT sensor), etc.) to give the PCM an idea of the load and climate under which the engine is operating.
^ Distributor ignition (DI) system
^ crankshaft position (CKP) sensor
^ ignition control module
^ Mass air flow (MAF) sensor
^ Throttle position (TP) sensor
^ Vehicle speed sensor (VSS)
^ Air conditioning clutch (ACC)
^ Engine coolant temperature sensor (ECT sensor)
TRANSMISSION INPUTS
Still other inputs are provided by the transaxle itself, from sensors such as the vehicle speed sensor (VSS), transmission range (TR) sensor (controlled by the placement of the shift lever) and the transmission fluid temperature (TFT) sensor.
^ Transmission fluid temperature sensor (TFT)
^ Transmission range sensor (TR)
^ Turbine shaft speed (TSS) sensor
OUTPUTS (SOLENOIDS)
Powertrain Control Module (PCM)-Outputs:
^ Transaxle solenoid body assembly
^ shift solenoid 1 (SS1)
^ shift solenoid 2 (SS2)
^ electronic pressure control (EPC) solenoid
^ torque converter clutch (TCC) solenoid
^ 3-2 timing coast clutch solenoid (3-2T/CCS)
^ Transmission control indicator lamp (TCIL)
DRIVER INPUTS
Some inputs are based on driver inputs, such as accelerator pedal position which is relayed to the PCM by the throttle position sensor (TP sensor).
^ Brake On/Off (BOO) switch
^ Transmission control switch