Jeep Grand Cherokee WK. Manual - part 1408

PRESSURE SWITCHES

The TCM relies on five pressure switches to monitor fluid pressure in the L/R, 2C, 4C, UD, and OD hydraulic cir-
cuits. The primary purpose of these switches is to help the TCM detect when clutch circuit hydraulic failures occur.
The switches close at approximately 23 psi and open at approximately 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:

GEAR

L/R

P/N

1ST

CL*

2ND

2ND PRIME

4TH

5TH

*L/R is closed if output speed is below 100 rpm in Drive and Manual 2. L/R is open in Manual 1.

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

REMOVAL

1. Remove the valve body from the transmission.

(Refer to 21 - TRANSMISSION/AUTOMATIC -
45RFE/545RFE/VALVE BODY - REMOVAL)

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AUTOMATIC TRANSMISSION - 545RFE - SERVICE INFORMATION

2. Remove the bolts (1) holding the transmission sole-

noid/TRS assembly onto the valve body.

3. Separate the transmission solenoid/TRS assembly

from the valve body.

INSTALLATION

1. Place TRS selector plate in the PARK position.

2. 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

3. Install the bolts (1) to hold the transmission sole-

noid/TRS assembly onto the valve body.

4. Tighten the solenoid assembly screws adjacent to

the arrows cast into the bottom of the valve body
first. Tighten the screws to 5.7 N·m (50 in.lbs.).

5. Tighten the remainder of the solenoid assembly

screws to 5.7 N·m (50 in.lbs.).

6. Install the valve body into the transmission.

SENSOR-TRANSMISSION TEMPERATURE

DESCRIPTION

The transmission temperature sensor is a thermistor that is integral to the Transmission Range Sensor (TRS).

OPERATION

The transmission temperature sensor is used by the TCM to sense the temperature of the fluid in the sump. Since
fluid temperature can affect transmission shift quality and convertor lock up, the TCM requires this information to
determine which shift schedule to operate in.

Calculated Temperature

A failure in the temperature sensor or circuit will result in calculated temperature being substituted for actual tem-
perature. Calculated temperature is a predicted fluid temperature which is calculated from a combination of inputs:

•

Battery (ambient) temperature

AUTOMATIC TRANSMISSION - 545RFE - SERVICE INFORMATION

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•

Engine coolant temperature

•

In-gear run time since start-up

BODY-VALVE

DESCRIPTION

The valve body consists of a cast aluminum valve body, a separator plate, and a transfer plate. The valve body
contains valves and check balls that control fluid delivery to the torque converter clutch, bands, and frictional
clutches. The valve body contains the following components :

•

Solenoid switch valve

•

Manual valve

•

Low/reverse switch valve

•

5 Accumulators

Valve Body Components

1 - LOW/REVERSE ACCUMULATOR

6 - OVERDRIVE ACCUMULATOR

2 - LOW/REVERSE SWITCH VALVE

7 - UNDERDRIVE ACCUMULATOR

3 - UPPER VALVE BODY

8 - 4C ACCUMULATOR

4 - MANUAL VALVE

9 - 2C ACCUMULATOR

5 - SOLENOID SWITCH VALVE

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AUTOMATIC TRANSMISSION - 545RFE - SERVICE INFORMATION

•

7 check balls

OPERATION

NOTE: Refer to the Hydraulic Schematics for a visual aid in determining valve location, operation and
design.

SOLENOID SWITCH VALVE

The Solenoid Switch Valve (SSV) controls the direction of the transmission fluid when the L/R-TCC solenoid is ener-
gized.

The Solenoid Switch Valve controls line pressure from the LR-TCC solenoid. In 1st gear, the SSV will be in the
downshifted position, thus directing fluid to the L/R clutch circuit. In 2nd, 3rd, 4th, and fifth gears, the solenoid switch
valve will be in the upshifted position and directs the fluid into the torque converter clutch (TCC) circuit.

When shifting into 1st gear, a special hydraulic sequence is performed to ensure SSV movement into the down-
shifted position. The L/R pressure switch is monitored to confirm SSV movement. If the movement is not confirmed
(the L/R pressure switch does not close), 2nd gear is substituted for 1st. A DTC will be set after three unsuccessful
attempts are made to get into 1st gear in one given key start.

MANUAL VALVE

The manual valve is a relay valve. The purpose of the
manual valve is to direct fluid to the correct circuit
needed for a specific gear or driving range. The man-
ual valve, as the name implies, is manually operated
by the driver with a lever located on the top of the
valve body. The valve is connected mechanically by a
cable to the gearshift mechanism. The valve is held in
each of its positions by a roller detent spring (2) that
engages the “roostercomb” of the TRS selector plate
(1).

1 - TRS SELECTOR PLATE
2 - DETENT SPRING
3 - CLUTCH PASSAGE SEALS

AUTOMATIC TRANSMISSION - 545RFE - SERVICE INFORMATION

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