Workshop

FORD 5R55N

AUTOMATIC TRANSMISSION SERVICE GROUP
Technical Service Information
7
Copyright © 2001 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 5R55N 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:
4 Multi-Plate Clutch Packs
Coast Clutch
Direct Clutch (Single Sided)
Forward Clutch
Intermediate Clutch (New)(Single Sided)
3 One-Way Clutches
Overdrive Sprag Clutch
Intermediate Sprag Clutch (New)
Low Sprag Clutch
3 Brake Bands
Overdrive Band
Intermediate Band
Low/Reverse Band
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
the transmission.
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.
There is also a Transmission Fluid Temperature
(TFT) sensor incorporated in the solenoid body
assembly that informs the PCM of the fluid
temperature. These units currently have a dedicated
"Air to Oil" cooler for the transmission.
Also incorporated in the solenoid body assembly is a
Reverse Pressure Switch that informs the PCM when
pressure is present in the reverse circuit. When
pressure is not present, the switch is open, and when
pressure is present the switch is closed.
The PCM also receives input signals from various
sensors and switches, located externally, that affect
proper transmission operation. The following will
provide a brief description of each of the sensors and
actuators used to control transmission operation.
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

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