2007 FORD FIESTA heating

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 -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

308-03-1 8 Manual Transmission/Transaxle 308-03-1 8
GENERAL PROCEDURES
Bearing Check
1. N0TE:Establish the cause of the damage Check the bearing is correctly lubricated. (.
and resolve it.
Check whether the bearing cage is damaged
at the top, side or at the openings is
damaged because of the unprofessional use
of a special tool or of the wrong tool.
lnstall a new bearing if necessary.
2. Check whether the ends of the taper rollers
are discoloured as a result of inadequate
lubrication or overheating, possibly through
excessive pre-load.
lnstall a new bearing and new seals if
necessary.
Check the bearing is correctly lubricated.
3. Check whether the ends of the taper rollers
are worn away due to incorrect installation,
excessive pre-load or faulty bearing seating.
lnstall a new bearing and new seals if
necessary.
4. Check whether the bearing surfaces are grey
or
greylblack with deposits between the
rollers.
lnstall a new bearing and new seals if
necessary.
Check the bearing is correctly lubricated.
5. Check whether the bearing ring surfaces are
grooved caused by static impact.
lnstall a new bearing if its surface is rough,
or if it is noisy.
2006.0 Fiesta 1212006 G21559en
procarmanuals.com

308-03-1 9 Manual Transmission/Transaxle 308-03-1 9
GENERAL PROCEDURES
6. N0TE:Overheating can cause loss of surface
hardness.
I Check for a dark blue colour caused by
overheating (yellow or brown is normal) due
to excessive pre-load or inadequate
lubrication.
Install a new bearing, new seals and check
other components as necessary.
7. Check the surfaces for abrasion due to metal
fatigue.
Install a new bearing and clean all other
( ') affected components as necessary.
2006.0 Fiesta 1212006 G21559en
procarmanuals.com