Cherokee, Grand Cherokee, 1999-2005

Transmission Range Sensor/Solenoid Assembly


Description & Operation

The transmission solenoid/TRS assembly, used on 45RFE/545RFE transmissions, 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 five pressure switches that feed information to the TCM.

Pressure Switches

The TCM relies on five pressure switches to monitor fluid pressure in the L/R, 2C, 4C, UD, and OD hydraulic circuits. The primary purpose of these switches is to help the TCM detect when clutch circuit hydraulic failures occur. The switches close at 23 psi and open at 11 psi, and simply indicate whether or not pressure exists. The switches are continuously monitored by the TCM for the correct states (open or closed) in each gear as shown in the following chart:

*L/R is closed if output speed is below 100 rpm in Drive and Manual 2.

NOTE: A Diagnostic Trouble Code (DTC) will set if the TCM senses any switch open or closed at the wrong time in a given gear.


Solenoids are used to control the L/R, 2C, 4C, OD, and UD friction elements. 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.

The continuity of the solenoids and circuits are periodically tested. Each solenoid is turned on or off depending on its current state. An inductive spike should be detected by the TCM during this test. If no spike is detected, the circuit is tested again to verify the failure. In addition to the periodic Testing, the solenoid circuits are tested if a speed ratio or pressure switch error occurs.

Removal & Installation

  1. Remove the valve body from the transmission.
  3. Remove the screws holding the transmission solenoid/TRS assembly onto the valve body.
  5. Separate the transmission solenoid/TRS assembly from the valve body.

To Install:

  1. Place TRS selector plate in the PARK position.
  3. Position the transmission solenoid/TRS assembly onto the valve body. Be sure that both alignment dowels are fully seated in the valve body and that the TRS switch contacts are properly positioned in the selector plate
  5. Install the screws to hold the transmission solenoid/TRS assembly onto the valve body.
  7. Tighten the solenoid assembly screws adjacent to the arrows cast into the bottom of the valve body first. Tighten the screws to 5.7 Nm (50 inch lbs.).
  9. Tighten the remainder of the solenoid assembly screws to 5.7 Nm (50 inch lbs.).
  11. Install the valve body into the transmission.

    Click image to see an enlarged view


    Click image to see an enlarged view