2007 FORD FIESTA Workshop Manual

Automatic Transmission/Transaxle -
Vehicles With: 4-Speed Automatic
307-01 -25 Transmission (AW81-40) 307-01 -25
DESCRIPTION AND OPERATION
Item Descriotion
I 1 I From the torque converter I
~l%ansmission input shaft I
1 4 1 Small sun gear I
1 6 1 Planet gear carrier I
1 8 1Short planet gear I
1 9 1 Long planet gear I
10 Annulus and
output wheel of the planetary
/ (gearset
I 11 I Intermediate gear stage I
1 12 1 Differential assembly I
1 13 12nd - 4th gear brake I
1 14 1 2nd gear one-way clutch I
1 15 1 Large sun gear I - --
1 16 14th gear brake I
1 17 1 3rdl4th gear clutch I
~Iianetary gearset, rear I
I B I Planetary gearset, front I
Drive is transmitted from the torque converter (I)
to the transmission input shaft (2) and via the
3rdl4th gear clutch (1 7) to the planet gear carrier
(6).
The large sun gear (15) is held by the 4th gear
brake
(16), the 2nd gear one-way clutch (14) and
the 2nd-4th gear brake
(1 3).
N0TE:The short planet gears (8) and the small
sun gear (4) co-rotate, but they have no influence
on the transmission ratio.
The long planet gears (9) drive the annulus (10) in
the same direction of rotation as the output from
the engine.
The annulus is fixedly connected to the output
wheel of the planetary
gearset and drives the
intermediate gear stage
(11) in the opposite
direction of rotation to the output from the engine.
The intermediate gear stage drives the differential
assembly
(12) in the same direction of rotation as
the output from the engine.
2006.0 Fiesta 1212006 G380528en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4-Speed Automatic
Transmission
(AW81-40)
DESCRIPTION AND OPERATION
Transmission ratio and power flow route
- reverse gear
2006.0 Fiesta 12/2006 G380528en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4-Speed Automatic
307-01 -27 Transmission (AW81-40) 307-01 -27
DESCRIPTION AND OPERATION
Item Description
I 1 I From the torque converter I
1 2 I Transmission input shaft I
1 4 ISmaII sun gear I
11 Planet gear carrier I
1 7 1 Reverse gear brake I
1 8 1Short planet gear I
1 9 1 Long planet gear I
10 Annulus and output wheel
of the planetary
I (gearset
I 11 I Intermediate gear stage I
1 12 1 Differential assembly I
1 15 1 Large sun gear I
1 18 1 Reverse gear clutch I
I A I Planetary gearset, rear I
I B I Planetary gearset, front I
Drive is transmitted from the torque converter (1)
to the transmission input shaft
(2) and via the
r reverse gear clutch (1 8) to the large sun gear (1 5).
The planet gear carrier
(6) is held by the reverse
gear brake
(7).
The large sun gear drives the long planet gears
(9) in the opposite direction of rotation to the output
from the engine.
N0TE:The short planet gears (8) and the small
sun gear (4) co-rotate, but they have no influence
on the transmission ratio.
The long planet gears drive the annulus (1
0) in the
opposite direction of rotation to the output from the
engine.
The annulus is fixedly connected to the output
wheel of the planetary
gearset and drives the
intermediate gear stage (I
I ) in the same direction
of rotation as the output from the engine.
The intermediate gear stage drives the differential
assembly (1 2) in the opposite direction of rotation
to the output from the engine.
2006.0 Fiesta 1212006 G380528en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4-Speed Automatic
Transmission
(AW81-40)
DESCRIPTION AND OPERATION
Transaxle Electronic Control System
Overview
--
2006.0 Fiesta 1212006 G380530en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4-Speed Automatic
Transmission (AW81-40)
DESCRIPTION AND OPERATION
Item Description
1 5 1 Generic Electronic Module (GEM) I
I
1 6 1 Turbine Shaft Speed (TSS) sensor I
1 7 1 Output Shaft Speed (OSS) sensor I
1
2
3
4
l tem Description
Transmission control unit
Data Link Connector (DLC)
Powertrain Control Module (PCM)
Instrument cluster
1 8 I Transmission Range (TR) sensor I
1 9 1 Starter inhibit relay I
1 10 1 Backup lamp relay I
11 Transmission Fluid Temperature (TFT)
I I sensor
1 12 loverdrive switch I
1 13 1 Driver's side door ajar switch I
1 14 1 Solenoid valves in the main control body 1
Transmission control unit
Item Description
Electrical connector, vehicle wiring
harness
connector, transmission wiring
harness
--
The transmission control unit is located in the
'engine compartment on the left-hand side member.
The transmission control unit evaluates incoming
signals and controls the actuators accordingly.
2006.0 Fiesta 1212006 G380530en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4-Speed Automatic
307-01 -30 Transmission (AW81-40) 307-01 -30
DESCRIPTION AND OPERATION
The transmission control unit can be diagnosed
with WDS via the DLC.
Gearshift strategies
Gearshift control
I A I Accelerator pedal position I
I B I vehicle speed 1
The current ratio is selected by the transmission
control unit either in accordance with the
requirements for low fuel consumption or in order
to meet the required driving performance.
The gearshift timing is selected in accordance with
a gearshift map which is programmed into the
control unit as a function of the accelerator pedal
position and the vehicle speed.
For kick-down (accelerator pedal pressed down at
least
95 %) the next lowest gear is selected, as
long as the engine speed allows it. All gearshift
timings are set by the transmission control unit to
the upper shift characteristic. The driver can feel the
kickdown point
in the
accelerator pedal as a slight increase in resistance
to the operation of the pedal.
This is influenced by the following variables:
accelerator pedal position and actuation,
vehicle speed,
brake pedal position,
selector lever position.
The following are actuated:
SSA shift solenoid valve,
SSB shift solenoid valve.
Hill climb mode
When the vehicle is in hill climb mode or towing a
trailer, the transmission control delays gearshifts
to prevent frequent shifting back and forth between
the gears.
2006.0 Fiesta 1u2oos
procarmanuals.com

Automatic TransmissionlTransaxle -
Vehicles With: 4-Speed Automatic
307-01 -31 Transmission (AW81-40) 307-01 -31
DESCRIPTION AND OPERATION
The transmission control unit determines hill climb
mode or trailer operation from the change in throttle
; valve position supplied by the PCM in relation to
the acceleration of the vehicle.
Depending on the driving resistance, the
transmission control unit chooses between two
gearshift maps which have been specially
programmed for this purpose and in which the shift
timings are again chosen as a function of the
accelerator pedal position and the vehicle speed..
Hill descent mode
The hill descent mode is used to take better
advantage of engine braking during hill descents.
A 'hill descent' situation is recognised by the
transmission control unit if the vehicle is
accelerating without operation of the accelerator
pedal.
If in addition the brake is also depressed then the
transmission control unit automatically shifts back
from 4th into 3rd gear.
( ' Cold start mode
In order to reach operating temperature as quickly
as possible under low ambient temperatures,
gearshifts into 4th gear and engagement of the
torque converter clutch (TCC) are suppressed if
one of the following conditions is met:
Transmission fluid temperature below +20 "C
Coolant temperature below - 40°C
The following are actuated: SSA shift solenoid valve,
SSB shift solenoid valve,
Shift solenoid valve, TCC.
Overheating protection mode
The overheating protection mode serves to protect
the transmission against overheating and the
serious damage that this can cause.
If the transmission fluid temperature reaches a
temperature of around 135
"C, the transmission
control employs a shift pattern designed to prevent
a further increase in the transmission fluid
temperature. When
the transmission fluid temperature drops
back below approx. 125
"C, the transmission
control exits the overheating protection mode.
The MIL warning lamp is actuated by the
transmission control unit if the transmission fluid
temperature reaches approximately 140
"C.
The MIL warning lamp goes out again when the
transmission fluid temperature drops back to below
around 130
"C.
Main line pressure control
In order to ensure the highest possible efficiency
of the automatic transmission and to limit the power
losses from the fluid pump, the main line pressure
is adapted accordingly by the main regulating valve
as a function of the accelerator pedal position
(driver torque demand) and the selector lever
position.
This is influenced by the following variables:
Accelerator pedal position and actuation
Selector lever position
The following are actuated:
Main 'regulating valve
Engagement of the TCC
The TCC is engaged in 3rd and 4th gear depending
on the current driving situation.
Engagement is controlled in accordance with the
shift map stored in the control unit.
This is influenced by the following variables:
Accelerator pedal position and actuation,
Vehicle speed,
Selector lever position,
Transmission fluid temperature,
Coolant temperature.
The following are actuated:
Shift solenoid valve, TCC.
Torque reduction during gearshifts
In order to improve the quality of gearshifts and to
avoid gearshift judder, the engine torque is reduced
by the PCM in response to a request from the
transmission control unit during gearshifts.
The engine torque is also reduced during
engagement and disengagement of the TCC.
2006.0 Fiesta 1212006 G380530en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4-Speed Automatic
307-01 -32 Transmission
(AW81-40) 307-01 -32
DESCRIPTION AND OPERATION
This is influenced by the following variables:
Engine speed,
Engine load,
Transmission input speed,
Vehicle speed.
The following are actuated:
PCM (torque reduction request signal via the
CAN databus).
Pressure control during gearshifts
In order to ensure that the engagement of the
clutches and brakes is as judder-free as possible,
the main line pressure is reduced during gearshifts.
This is influenced by the following variables:
Enginespeed,
Engine load,
Transmission input speed,
Vehicle speed.
The following are actuated:
Main regulating valve.
Shift timing adaptation during upshifts
In order to ensure that the engagement of the
clutches and brakes is as judder-free as possible,
the timing of the gearshift processes is monitored
during upshifts.
In the event of any discrepancy from the target
values, the main line pressure is adapted
accordingly during the next gearshift.
The shift timing adaptation during upshifts is only
active at transmission fluid temperatures between
50
"C and 120 "C.
This is influenced by the following variables:
Engine load,
Accelerator pedal position,
Transmission input speed,
Vehicle speed,
Transmission fluid temperature,
Selector lever position.
The following are actuated:
Main regulating valve.
Shift timing adaptation during shifts from
3rd to 4th gear
The shift from 3rd gear into 4th gear is the only
gearshift during which a clutch is disengaged and
a brake is engaged simultaneously.
In order to control the synchronized switching of
the two components as exactly as possible, the
shifl timing solenoid valve is actuated accordingly.
In order to ensure that this particular gearshift is
performed as judder-free as possible throughout
the service life of the transmission, the gearshift is
monitored by the two rotational speed sensors and
the actuation of the shift timing solenoid valve is
adapted accordingly.
The shift timing adaptation for gearshifts from 3rd
gear into 4th gear is only active at transmission
fluid temperatures between 30
"C and 120 "C.
This is influenced by the following variables:
Engine load,
Accelerator pedal position,
Transmission input speed,
Vehicle speed,
Transmission fluid temperature,
Selector lever position.
The following are actuated:
Shift timing solenoid valve.
Shift timing adaptation during shifts from
4th to 3rd gear
The shift from 4th gear into 3rd gear is the only
gearshift during which a brake is disengaged and
a clutch is engaged simultaneously.
In order to control the engagement of the clutch as
precisely as possible, the main regulating valve is
actuated accordingly in order to build up the
actuating pressure at exactly the right time.
In order to ensure that this particular gearshift is
performed as judder-free as possible throughout
the service life of the transmission, the gearshift is
monitored by the two rotational speed sensors and
the actuation of the main regulating valve is
adapted accordingly.
The shift timing adaptation for gearshifts from 4th
-
gear into 3rd gear is only active at transmission (
fluid temperatures between 20 "C and 120 "C. .
2006.0 Fiesta 1212006 G380530en
procarmanuals.com