Dakota 4WD V8-4.7L VIN J (2007)
Fluid Pressure Sensor/Switch: Description and Operation
545RFE Automatic Transmission
Description
DESCRIPTION
The TCM utilizes a closed-loop system to control transmission line pressure. The system contains a variable force style solenoid, the Pressure Control
Solenoid, which is part of the pressure switch assembly. The solenoid is duty cycle controlled by the TCM to vent the unnecessary line pressure supplied
by the oil pump back to the pump inlet. The system contains a Line Pressure Sensor, which is a direct input to the TCM. The line pressure sensor
monitors the transmission line pressure and completes the feedback loop to the TCM. The TCM uses this information to adjust its control of the pressure
control solenoid to achieve the desired line pressure.
Operation
OPERATION
The TCM calculates the desired line pressure based upon inputs from the transmission and engine. The TCM calculates the torque input to the
transmission and uses that information as the primary input to the calculation. The line pressure is set to a predetermined value during shifts, to ensure
consistent shift quality. During all other operation, the desired line pressure value is adjusted based on torque level and other transmission requirements.
Description
DESCRIPTION
The transmission solenoid/TRS assembly is internal to the transmission and mounted on the valve body assembly. The assembly consists of six solenoids
that control hydraulic pressure to the six friction elements (transmission clutches), and the torque converter clutch. The pressure control solenoid is
located on the side of the solenoid/TRS assembly. The solenoid/TRS assembly also contains the Transmission Range Sensor (TRS) and five pressure
switches that feed information to the TCM.
Operation
OPERATION
SOLENOIDS
Solenoids are used to control the L/R, 2C, 4C, OD, and UD friction elements. The reverse clutch is controlled by line pressure and the position of the
manual valve in the valve body. All the solenoids are contained within the Solenoid and Pressure Switch Assembly. The solenoid and pressure switch
assembly contains one additional solenoid, Multi-Select (MS), which serves primarily to provide 2nd and 3rd gear limp-in operation.
The solenoids receive electrical power from the Transmission Control Relay through a single wire. The TCM energizes or operates the solenoids
individually by grounding the return wire of the solenoid as necessary. When a solenoid is energized, the solenoid valve shifts, and a fluid passage is
opened or closed (vented or applied), depending on its default operating state. The result is an apply or release of a frictional element.
The MS and UD solenoids are normally applied to allow transmission limp-in in the event of an electrical failure.
