Operation; Transmission Solenoid/Trs Assembly; Description - Dodge Dakota Sport 2001 Service Manual

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21 - 528
AUTOMATIC TRANSMISSION - 45RFE
TRANSMISSION SOLENOID/
TRS ASSEMBLY

DESCRIPTION

The transmission solenoid/TRS assembly is inter-
nal to the transmission and mounted on the valve
body assembly (Fig. 115). 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 sole-
noid is located on the side of the solenoid/TRS assem-
bly. The solenoid/TRS assembly also contains five
pressure switches that feed information to the TCM.
Fig. 115 Transmission Solenoid/TRS Assembly
1 - PRESSURE CONTROL SOLENOID
2 - TRANSMISSION RANGE SENSOR
3 - 23-WAY CONNECTOR
4 - SOLENOID PACK

OPERATION

SOLENOIDS
Solenoids are used to control the L/R, 2C, 4C, OD,
and UD friction elements. The reverse clutch is con-
trolled by line pressure and the position of the man-
ual 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 individ-
ually 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 operat-
ing state. The result is an apply or release of a fric-
tional element.
The MS and UD solenoids are normally applied to
allow transmission limp-in in the event of an electri-
cal 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 pres-
sure switch error occurs.
PRESSURE SWITCHES
The TCM relies on five pressure switches to moni-
tor 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 cir-
cuit 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:
GEAR
L/R
2C
R
OP
OP
P/N
CL
OP
1ST
CL*
OP
2ND
OP
CL
2ND
OP
OP
PRIME
D
OP
OP
FOURTH
OP
OP
*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.
AN
4C
UD
OD
OP
OP
OP
OP
OP
OP
OP
CL
OP
OP
CL
OP
CL
CL
OP
OP
CL
CL
CL
OP
CL

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