Commander 2WD V6-3.7L VIN K (2006)
Control Module: Description and Operation
MODULE-TRANSMISSION CONTROL
DESCRIPTION
The transmission control module (TCM) (1) is mounted to the dash panel (2), under the dash panel silencer pad, just to the right of the steering column.
The electronic control system consists of various components providing inputs to the TCM. The TCM monitors transmission sensors, shifter assembly,
and bus messages to determine transmission shift strategy. After shift strategies are determined, the TCM controls the actuation of transmission
solenoids, which controls the routing of hydraulic fluid within the transmission, by moving a sequence of four valves to make a shift occur.
The system performs its functions based on continuous real-time sensor feedback information. In addition the TCM receives information from the rest of
the vehicle over the CAN C bus. The CAN C bus is a high-speed communication bus that allows real time control capability between various controllers.
Most messages are sent every 20 milliseconds. This means critical information can be shared between the transmission, engine, and ABS controllers.
The CAN C bus is a two wire bus with a CAN C Bus (+) circuit and a CAN C Bus (-) circuit. These circuits are twisted pairs in the harness to reduce the
potential of radio and noise interference.
The transmission control system automatically adapts to changes in engine performance, vehicle speed, and transmission temperature variations to
provide consistent shift quality. The control system ensures that clutch operation during up-shifting and downshifting is more responsive without
increased harshness. The TCM activates the solenoid valves and moves valves in the valve body to achieve the necessary gear changes. The required
pressure level is calculated from the load condition, engine speed. Vehicle speed (from ABS module) and transmission oil temperature, matched to the
torque to be transmitted. Power for the transmission system is supplied through the shifter mechanism (no transmission control relay).
OPERATION
The transmission control module (TCM) determines the current operating conditions of the vehicle and controls the shifting process for shift comfort and
driving situations. It receives this operating data from sensors and broadcast messages from other modules.
The TCM uses inputs from several sensors that are directly hardwired to the controller and it uses several indirect inputs that are used to control shifts.
This information is used to actuate the proper solenoids in the valve body to achieve the desired gear.
The shift lever sensor assembly (SLSA) has sensors that are monitored by the TCM to calculate shift lever position. The reverse light switch, an integral
part of the SLSA, controls the reverse light relay control circuit. The Brake/ Transmission Shift Interlock (BTSI) solenoid and the park lockout solenoid
(also part of the SLSA) are controlled by the TCM.
The ECM and ABS broadcast messages over the controller area network (CAN C) bus for use by the TCM. The TCM uses this information, with other
inputs, to determine the transmission operating conditions.
The TCM:
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determines the momentary operating conditions of the vehicle.
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controls all shift processes.
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considers shift comfort and the driving situation.
