FORD FIESTA 2007 Workshop Manual

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

Automatic Transmission/Transaxle -
Vehicles With: 4Speed Automatic
307-01 -33 Transmission (AW81-40) 307-01 -33
DESCRIPTION AND OPERATION
This is influenced by the following variables: Vehicle
speed,
Engine load, Transmission fluid temperature.
Accelerator pedal position, The following are actuated:
Transmission input speed, SSA shift solenoid valve,
Vehicle speed,
Transmission fluid temperature,
Selector lever position.
The
following are actuated:
Main
regulating valve.
Reverse gear safety strategy
SSB shift solenoid valve.
Torque reduction when pulling away
In order to protect the clutches against excessively
high torque when pulling away, the PCM reduces
the engine torque in response to a request from
the transmission
control.
If the accelerator pedal is depressed while the
The transmission control unit prevents shifts into vehicle is pulling away, then the transmission reverse gear while the vehicle is driving forwards, control unit sends a corresponding signal as otherwise serious transmission damage can be requesting a torque reduction via the CAN databus. caused.
The reverse gear safety strategy is active when This
is influenced by the
following variables:
reverse gear is engaged with the selector lever at ' Selector lever position,
vehicle speeds in excess of 11 kmlh. Accelerator pedal position,
In this
case the transmission control unit actuates ' Engine speed,
the shift timing solenoid valve, as a result of which Transmission input speed,
the actuating pressure does not reach the reverse
. Vehicle speed. gear clutch or the reverse gear brake.
The following are actuated:
The reverse gear safety strategy is deactivated
PCM (torque reduction request signal via the
when the vehicle speed is below 9 kmlh. The
actuating pressure can then reach the reverse gear CAN
databus).
clutch and the reverse gear brake and the gearshift
into reverse gear is performed.
Selector lever positions
This is influenced by the following variables:
Vehicle speed,
Selector lever position.
The
following are actuated:
Shift timing solenoid valve.
Selector lever position "P"
No gear is engaged in selector lever position "P".
The parking
pawl is engaged manually via the
selector lever cable and the selector shaft.
Avoidance of gearshift judder during
engagement of a transmission range Selector
lever position "R"
In order to prevent gearshift judder when moving The reverse gear is eWaged in selector lever
the selector lever from N to D, the transmission position "R.
control unit initially shifts into
2nd gear instead of
1 st gear, and then immediately shifts back into I st
gear before the gearshift process is finished. Selector lever position "N"
This reduces the amount of gearshift judder during No gear is engaged in selector lever position WNW. engagement of a forward drive range.
The powertrain is not blocked. This is influenced by the following variables:
Selector lever position,
Accelerator pedal position,
Transmission input speed,
2006.0 Fiesta 1212006 G380530en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4Speed Automatic
307-01 -34 Transmission (AW81-40) 307-01 -34
DESCRIPTION AND OPERATION
Selector lever position "D" In selector lever position "2" engine braking is
effective when the vehicle is coasting.
In selector lever position
"D" the transmission
control will allow all gears to be engaged provided
the overdrive switch is not operated.
Selector lever position "1"
If the overdrive switch is pressed then the
Only the first gear is engaged when the selector
transmission control prevents gearshifts into 4th
lever is in position ,,. gear or shifts back into 3rd gear.
Selector lever position "2"
If the selector lever is moved to position "1" at
higher speeds than are permitted for first gear, then
the transmission control delays the downshift until
the vehicle speed has slowed down enough.
-
Only the second gear is engaged when the selector In selector lever position ,, engine braking is lever is in position "2". Gearshifts into 1st gear are effective when the vehicle is not permitted.
If the selector lever is moved to position
"2" at
higher speeds than are permitted for second gear,
then the transmission control delays the downshift until the vehicle speed has slowed down enough.
Signal transmission on the CAN databus
CAN Low
E48 1 88
Item Description Item Description
I 1 1 Transmission control unit 1 3 1 Instrument cluster
2006.0 Fiesta 1~2006 G380530en
2 PCM 4 DLC
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4Speed Automatic
307-01 -35 Transmission (AW81-40) 307-01 -35
DESCRIPTION AND OPERATION
Engine speed
1 The engine speed is detected by the crankshaft
position (CKP) sensor and passed on to the PCM.
The engine speed is transmitted from the PCM via
the CAN
databus to the transmission control unit.
The transmission control unit uses this signal for:
Torque reduction during gearshifts,
Pressure control during gearshifts.
Engine load
The PCM determines a load signal which is
transmitted via the CAN
databus to the
transmission control unit.
The transmission control unit uses this signal for:
Torque reduction during gearshifts,
Pressure control during gearshifts,
Shift timing adaptation during upshifts,
Shift timing adaptation during shifts from 3rd to
4th gear,
Hill climb mode,
( ' Hill descent mode. ' ,
Torque reduction request signal
Before performing a gearshift, the transmission
control unit sends a signal via the CAN
databus to
the PCM requesting a torque reduction.
The PCM then reduces the engine torque, ensuring
that the gearshift is as smooth and judder-free as
possible.
Brake signal
The PCM receives a signal from the stoplamp
switch when the brake pedal is depressed.
This signal is transmitted via the CAN
databus to
the transmission control unit.
The transmission control unit uses this signal for:
Gearshift control,
Engagement of the TCC
Accelerator pedal position
The PCM receives the current accelerator pedal
position signal from the Accelerator Pedal Position
(APP) sensor.
This signal is transmitted via the CAN
databus to
the transmission control unit.
The transmission control unit uses this signal for:
Controlling the main line pressure,
Gearshift control,
Engagement of the TCC,
Shift timing adaptation during upshifts,
Shift timing adaptation during shifts from 3rd to
4th gear,
Shift timing adaptation during shifts from 4th to
3rd gear,
Avoidance of gearshift judder during
engagement of a transmission range,
Torque reduction when pulling away.
Coolant temperature
The coolant temperature is detected by the Engine
Coolant Temperature (ECT) sensor and passed
on to the PCM.
This signal is transmitted via the CAN
databus to
the transmission control unit.
The transmission control unit uses this signal for:
Cold start mode,
Engagement of the TCC
Selector lever position
The transmission control unit transmits the selector
lever position to the instrument cluster.
The instrument cluster uses the signal to send a
request for a warning tone to the GEM when the
selector lever is not in position "P" and the driver's
door is opened.
-
2006.0 Fiesta 1212006 G380530en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4-Speed Automatic
307-01 -36 Transmission (AW81-40) 307-01 -36
DESCRIPTION AND OPERATION
Actuation of the MIL warning lamp Warning tone request
The information required to actuate the
MIL The
driver's door is open.
warning lamp is sent the transmission control The instrument cluster passes on the warning tone unit to the instrument cluster.
request to the GEM. The GEM generates the
warning tone.
I I I
Actuation of the overdrive indicator lamp
I
The overdrive indicator lamp is located on the
instrument panel.
The MIL warning lamp
is actuated by the The transmission control unit sends
a warning tone
instrument cluster if there are serious faults in the request
to the instrument cluster if the following
transmission control or if the transmission fluid conditions are
met:
temperature is excessively high.
The selector lever is not in position "P",
The information required to actuate the overdrive
indicator lamp is sent from the transmission control
unit when the overdrive switch on the selector lever
is pressed.
2006.0 Fiesta 1u2oos G380530en
procarmanuals.com

Automatic TransmissionlTransaxle -
Vehicles With: 4-Speed Automatic
307-01 -37 Transmission
(AW81-40) 307-01 -37
DESCRIPTION AND OPERATION
Sensors
OSS sensor
TSS sensor
The TSS sensor is an inductive pickup.
It measures the transmission input speed via the
outer plate carrier of the
3rdl4th gear clutch and
sends the signal to the transmission control unit.
The transmission control unit uses this signal for:
Torque reduction during gearshifts,
Pressure control during gearshifts,
Shift timing adaptation during upshifts,
Shift timing adaptation during shifts from 3rd to
4th gear,
Shift timing adaptation during shifts from 4th to
3rd gear,
Avoidance of gearshift judder during
engagement of a transmission range,
Torque reduction when pulling away.
Consequences of signal failure:
No TCC,
no torque reduction,
no shift timing adaptation,
no 4th gear. The
OSS sensor is a Hall sensor.
It is mechanically connected via a gear to the input
wheel of the differential assembly.
It measures the vehicle speed via the input wheel
of the differential assembly and sends the signal
to the transmission control unit.
The transmission control unit uses this signal for:
Gearshift control,
Engagement of the TCC,
Torque reduction during gearshifts,
Pressure control during gearshifts,
Shift timing adaptation during upshifts,
Shift timing adaptation during shifts from 3rd to
4th gear,
Shift timing adaptation during shifts from 4th to
3rd gear,
Reverse gear safety strategy,
Avoidance of gearshift judder during
engagement of a transmission range,
Torque reduction when pulling away,
Hill climb mode,
Hill descent mode.
2006.0 Fiesta 1212006 G380530en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4Speed Automatic
307-01 -38 Transmission (AW81-40) 307-01 -38
DESCRIPTION AND OPERATION
Consequences of signal failure:
NoTCC,
no torque reduction, no shift timing adaptation,
no 4th
gear.
TR sensor
The TR sensor serves to signal the currently
selected transmission range to the transmission
control unit.
It is a switch which transmits the selected
transmission range directly to the transmission
control unit.
In addition, the starter inhibit relay is actuated by
the PCM via the TR sensor when the selector lever
is in the positions "P" or
N.
In selector lever position "R the backup lamp relay
is also actuated via the TR sensor.
The transmission control unit uses this signal for:
Controlling the main line pressure,
Gearshift control,
Engagement of the TCC,
Shift timing adaptation during upshifts,
Shift timing adaptation during shifts from 3rd to
4th gear,
Shift timing adaptation during shifts from 4th to
3rd gear,
Reverse gear safety strategy,
Avoidance of gearshift judder during
engagement of a transmission range,
Torque reduction when pulling away.
Consequences of signal failure:
NoTCC,
no shift timing adaptation.
2006.0 Fiesta 1212006 G380530en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4-Speed Automatic
307-01 -39 Transmission (AW81-40) 307-01 -39
DESCRIPTION AND OPERATION
TFT sensor Overdrive switch
The TFT sensor is located in the oil pan on the
main control body and is part of the transmission
wiring harness.
It measures the current transmission fluid
temperature and sends the signal to the
transmission control unit.
The transmission control unit uses this signal for:
Cold start mode,
Engagement of the TCC,
Shift timing adaptation during upshifts,
' , Shift timing adaptation during shifts from 3rd to
4th gear,
Shift timing adaptation during shifts from 4th to
3rd gear,
Overheating protection mode.
Consequences of signal failure:
NoTCC,
no shift timing adaptation,
no 4th gear. The overdrive switch
is located on the selector
lever.
It allows the driver to suppress or enable gearshifts
into 4th gear when
"D" is selected.
The signal from the overdrive switch is transmitted
to the transmission control unit.
When gearshifts into 4th gear are suppressed, the
transmission control unit sends a corresponding
signal via the CAN
databus to the instrument
cluster. The instrument cluster then actuates the
overdrive indicator lamp.
Consequences of signal failure:
no suppression of gearshifts into 4th gear.
2006.0 Fiesta 1212006 G380530en
procarmanuals.com

Automatic Transmission/Transaxle -
Vehicles With: 4-Speed Automatic
307-01 -40 Transmission (AW81-40)
307-01 -40
DESCRIPTION AND
OPEMION
Driver's side door ajar switch
The door ajar switch is located in the door lock on
the driver's side.
When the door is closed a ground connection is
signalled to the transmission control unit.
When the door is opened this ground connection
is interrupted.
The transmission control unit uses the signal from
the driver's side door ajar switch to warn the driver
if the selector lever is not in position
"P" and the
driver's door is open.
In this case the transmission control unit transmits
the warning tone request via the CAN
databus to
the instrument cluster.
The instrument cluster passes this request on to
the GEM, which then generates a warning tone.
Consequences of signal failure:
no warning tone request.
Actuators
Main regulating valve
Item Description
I 1 I Main regulating valve I
The main regulating valve is a proportional valve
which converts the applied electric current into a
proportional hydraulic pressure.
The currentless state corresponds to maximum
pressure.
/
The main regulating valve is used to determine the
main line pressure and therefore the actuating
pressure for the clutches and brakes.
Consequences of signal failure:
hydraulic emergency running mode.
SSA and SSB shift solenoid valves
Item Description
2006.0 Fiesta 1212006 G380530en
1
2
SSA
SSB
(- t..
procarmanuals.com