Workshop

FORD 5R55N

AUTOMATIC TRANSMISSION SERVICE GROUP
Technical Service Information
8
Copyright © 2001 ATSG
MASS AIR FLOW (MAF) SENSOR
ELECTRONIC COMPONENTS
OUTPUT SHAFT SPEED (OSS) SENSOR
PRESSURE CONTROL SOLENOIDS (PCA, PCB, PCC)
SHIFT SOLENOIDS (SSA, SSB, SSC, SSD)
TORQUE CONVERTER CLUTCH (TCC) SOLENOID
TRANSMISSION FLUID TEMPERATURE (TFT) SENSOR
TRANSMISSION CONTROL SWITCH (TCS)
THROTTLE POSITION SENSOR (TPS)
DIGITAL TRANSMISSION RANGE (TR) SENSOR
TURBINE SHAFT SPEED (TSS) SENSOR
INTERMEDIATE SHAFT SPEED (ISS) SENSOR
The Mass Air Flow (MAF) sensor, located in the air
cleaner inlet tube, measures the amount of air flowing
into the engine and sends this information (engine
load) to the PCM. For transmission strategies the
MAF is used to regulate electronic pressure control,
shift timing and torque converter clutch scheduling.
The Transmission Control Switch (TCS), located
within the manual range selector assembly (Base
Shifter Only), and the PCM uses this signal to disable
5th gear operation and activates the coast clutch. At
the same time the PCM changes the PRNDL indicator
on the instrument panel to display "D4". When the
driver moves the range selector back to the "D5"
position, 5th gear operation is resumed, coast clutch is
released and the instrument panel indicator will
display "D5".
The Throttle Position Sensor is a potentiometer
located on the throttle body and is used to detect
throttle plate position and send this information to the
PCM. The PCM uses this information for shift
scheduling, pressure control and TCC control.
The Digital Transmission Range (TR) sensor is
located on the outside of the transmission at the
manual shift lever. The digital TR sensor completes
the start circuit in Park and Neutral, and the back-up
lamp circuit in Reverse. The digital TR sensor also
opens or closes a set of four switches that are
monitered by the PCM to determine the position of
the manual lever (P, R, N, D5, 3, 2, 1).
The Turbine Shaft Speed (TSS) sensor is mounted
externally on the transmission case, and triggered by
the overdrive carrier. The PCM uses TSS to help
determine appropriate operating pressures and TCC
operation.
The Output Shaft Speed (OSS) sensor is mounted
externally on the transmission case, and triggered by a
speed rotor on the parking gear on the output shaft.
The PCM uses OSS to determine appropriate shift
speed scheduling, operating pressures and TCC
operation.
The Pressure Control solenoids PCA, PCB and PCC
are located in the solenoid body assembly and are a
variable-force style (VFS) solenoid. The VFS type
solenoid is an electro-hydraulic actuator that
combines a solenoid and a regulating valve. The
PCM varies the current to all three pressure control
solenoids.
The line pressure tap is used to verify output pressure
from "PCA" or "PCB" by turning off either one, while
verifying the output from the other solenoid. The
second pressure tap is used to verify the output
pressure from "PCC" solenoid.
The four On-Off Shift Solenoids are three-way,
normally open style solenoids, and also located in the
solenoid body assembly. The four shift solenoids,
(SSA, SSB, SSC, SSD), provide gear selection of 1st
through 5th and reverse gears by directing control
pressures to the appropriate element. Coast braking
and manual gear selections are also controlled by the
shift solenoids.
The Torque Converter Clutch (TCC) solenoid is a
pulse width modulating type of solenoid and is used to
control the apply and release of the TCC. Like the
others, it is located in the solenoid body assembly.
The Transmission Fluid Temperature (TFT) sensor
is a thermister type sensor that varies a reference
signal to the PCM. The PCM uses this information to
determine fluid temperature. The shift schedule is
compensated when fluid is cold. The PCM also
inhibits TCC operation, and compensates pressure
control solenoids when fluid is cold. The PCM uses
TFT signal to help determine shift scheduling, TCC
operation and pressure control requirements.
The Intermediate Shaft Speed (ISS) sensor is
mounted externally on the case, and triggered by the
sun gear shell. The PCM uses ISS to aid in
determining appropriate pressure requirements.

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