AUTOMATIC TRANSMISSION SERVICE GROUP
Technical Service Information
Copyright © 2004 ATSG
GENERAL DESCRIPTION AND OPERATION
AIR CONDITIONING CLUTCH
BRAKE PEDAL POSITION (BPP) SWITCH
ENGINE COOLANT TEMPERATURE (ECT) SENSOR
ELECTRONIC IGNITION (EI) SYSTEM
INTAKE AIR TEMPERATURE (IAT) SENSOR
The 5R55W/S is a fully automatic rear wheel drive
transmission. It provides Park, Reverse, Neutral, and
five forward speeds with 5th gear being overdrive
Internally it looks similar to the previous 5R55E
transmission, but there are very few minor
components that are actually the same, so be very
cautious during the rebuild process. The major
components used in this unit are as follows:
3 Multi-Plate Clutch Packs
Direct Clutch (Single Sided)
2 One-Way Clutches
Overdrive Sprag Clutch
Low Sprag Clutch
3 Brake Bands
3 Compound Planetary Gear Sets
Overdrive Planetary Set
Forward Planetary Set
Rear Planetary Set
The shift pattern is controlled electronically with
four (On-Off) solenoids that recieve a ground signal
from the PCM (Powertrain Control Module). The
PCM will vary shift points, as it is constantly
interpreting numerous electronic signals from various
operational sensors located on the vehicle and inside
Line pressure and shift feel are also controlled
electronically with three Pressure Control solenoids,
referred to as PCA, PCB, and PCC. The PCM varies
the current to the pressure control solenoids and Ford
refers to them as Variable Force Solenoids.
The PCM also controls application of the converter
clutch and apply feel electronically, with a TCC
solenoid, which is also Variable Force style.
All solenoids are incorporated in the "Solenoid
Body", located on the valve body, and are not serviced
seperately. You must purchase the entire solenoid
body assembly, if necessary.
The PCM also receives input signals from various
sensors and switches, located internally and
externally, that affect proper transmission operation.
The following will provide a brief description of each
of the sensors and actuators used for transmission
This switch is located on the suction accum/drier and
when the A/C is engaged, operating pressures are
adjusted to compensate for the additional engine load.
This switch is located on the brake pedal and tells the
PCM when the brakes are applied. The TCC is
disengaged when the brakes are applied. The BPP
switch closes when the brakes are applied and open
when they are released.
This sensor detects temperature of engine coolant
and supplies the information to the PCM. The PCM
uses this information to control Torque Converter
Clutch (TCC) operation.
The ignition control module generates a Profile
Ignition Pickup (PIP) signal (engine rpm) and sends it
to the PCM. The PCM uses PIP signal in the
transmission strategy for WOT shift control, TCC
control and operating pressures.
The Intake Air Temperature (IAT) sensor, located in
the air cleaner outlet tube, is also used in the
transmission strategy to determine control pressures.
Continued On Next Page
MASS AIR FLOW (MAF) 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.