Transmission Electronic System
The transmission control module (TCM) and its input/output network control the following operations:
Shift timing
Clutch pressure (shift feel)
Line pressure (shift feel)
Torque converter clutch
In addition, the TCM receives input signals from certain transmission-related sensors. The TCM also uses these signals when determining transmission operating strategy.
Using all of these input signals, the TCM 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 TCM uses 6 pressure control solenoids and one shift solenoid to control transmission operation.
The following provides a brief description of each of the sensors and actuators used to control transmission operation.
Transmission Control Module (TCM) and Main Control Valve Body
The TCM and main control valve body are a combination of hydraulic and electronic control units. Both of these modules are installed in the transmission inside the transmission fluid pan.
Transmission Control Module (TCM)
The TCM for the transmission is mounted on top of the main control valve body. The control module for the transmission has been designed to operate correctly in the environment in which the TCM is located.
The TCM is activated and deactivated by the ignition supply and is connected to the transmission link harness by a 16-pin connector.
The TCM controls the operation of the transmission. The TCM processes information in both analog and digital forms, such as:
transmission input speed.
transmission output speed.
throttle position.
gear selection.
engine torque.
engine speed.
transmission fluid temperature.
brake pedal position.
engine oil temperature.
engine coolant temperature.
ABS wheel speed.
The information is then used by the TCM to decide which shift pattern to select and for shift energy management. Electro-hydraulic solenoid valves and pressure regulators control the transmission gear changes.
Five pressure regulators and one solenoid valve are used to control direct transmission fluid flow to select internal clutches and control the fluid pressure at the clutch. A separate pressure regulator is used exclusively for torque converter clutch control.
The TCM monitors all transmission inputs and outputs to confirm correct system operation. If a fault occurs, the TCM is able to carry out default action. It informs the driver of the problem through the instrument cluster diagnostic MIL light.
The TCM will shut down if the TCM hardware temperature rises above a predetermined temperature. Prior to shutting down, the TCM will log a fault code and enter a mechanical limp-home mode.
You may want to disconnect the battery for about 15-20 min to see if it resets itself.
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