All-wheel drive control unit
E100663
14
3
2
5
Description
Item
Electronic Control Unit
1
Control valve
2
Pressure/temperature sensor
3
Electrical connection CAN (controller area
network) databus
4
Electric feed pump connection
5
The all-wheel drive control unit is bolted directly to
the housing of the Haldex clutch.
It forms one unit made up of the control valve, a
pressure/temperature sensor, and a control
module. It receives signals from the PCM and from
the ABS control module via the CAN data bus. The
control module in the control unit uses these
signals to determine the fluid pressure that is
needed to actuate the clutch plates depending on
the requirement. This determines how much torque
should be transmitted to the rear wheels. All-wheel
drive is deactivated if a fault occurs in the all-wheel
drive control unit.
A preload of approx. 80 Nm is always present at
the Haldex clutch. The temperature sensor of the Haldex clutch is
installed near the control valve in the control unit
and is surrounded by the hydraulic fluid. The
temperature is transmitted to the control module
and is used for adaptation to the changing viscosity
of the hydraulic fluid. If the hydraulic fluid is cold,
the control valve has to be opened slightly more
than requested. This allowance has to be reduced
as the temperature increases. The normal working
temperature of the hydraulic fluid is between +40
°C and +60 °C. If the temperature rises above 100
°C, the clutch is depressurised; if the temperature
falls below 95 °C, the clutch is pressurised again.
All-wheel drive is deactivated and a diagnostic
trouble code set if a fault occurs in the temperature
sensor.
With Haldex Generations I and II, the control valve
was actuated via a stepper motor. With Haldex
Generation III, the stepper motor has been omitted.
The control valve is now actuated via a solenoid
valve. The solenoid valve is actuated by the control
module in the all-wheel drive control unit by means
of pulse width modulation. The pulse width
modulation determines the position of the
adjustment spindle and thus the opening cross
section of the return hole. This is how the pressure
at the working piston of the plates is determined.
If the return hole is fully closed, maximum pressure
is applied to the plates. If the return hole is fully
open, the plates are unpressurized.
Electric feed pump
The electric feed pump is installed in the clutch
unit. It works according to the gerotor principle.
The main purpose of the feed pump is to fill the
pressure accumulator and the space behind the
pump plunger with hydraulic fluid, thereby ensuring
a fast response time of the Haldex clutch. The feed
pump used in the third generation is designed to
achieve an even higher pressure than the base
pressure of 4 bar. It is supplied with current by the
control module in the all-wheel drive control unit
when the engine is running above approx. 400 rpm.
Pressure control - 3rd generation
Haldex clutch
G1076981en2008.50 Kuga8/2011
205-02-
10
Rear Drive Axle/Differential
205-02- 10
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6
7
8
9
10
11
1
2
3
4
5
6
7
8
9
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E114914
Description
Item
Haldex clutch fluid
1
Inlet filter
2
Electric feed pump
3
Filters4
Pressure accumulator
5Description
Item
Control valve
6
Dished washer
7
Ring piston
8
Clutch plate pack
9
Return pressure accumulator
10
Return control valve
11
Full torque is available at any time on the 4th
generation Haldex clutch because the pressure is
not dependent on the difference in the speeds of
rotation. This is used for instance to activate the
Haldex clutch for better traction when moving off.
On the 4th generation Haldex clutch, the preload
function which applied 80 Nm to the plates in the
3rd generation is no longer required.
On request from the control unit and at engine
speeds above 400 rpm, the electric feed pump runs
and maintains the storage pressure at about 30
bar.
A pressure reducing valve acts as a control valve,
allowing the all-wheel drive control unit to control
the pressure with much greater precision. The
all-wheel drive control unit monitors the position and function of the control valve. The control valve
distributes the pressure, depending on the
requirements, across its three outlet openings
(storage pressure, working pressure, return).
From the storage pressure (30 bar) and depending
on the requirements, the control valve regulates a
working pressure of 0 - 17 bar, which is applied to
the ring piston. At 17 bar working pressure, the
maximum torque of 1000 Nm is transferred to the
rear wheels. The all-wheel drive control unit
ensures the best possible performance under all
driving conditions, for all road conditions and
independent of the speed.
G1076981en2008.50 Kuga8/2011
205-02-
16
Rear Drive Axle/Differential
205-02- 16
DESCRIPTION AND OPERATION
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4. Remove the vacuum hose from the brakebooster. Manifold vacuum should be available
at the brake booster end of the hose with the
engine at idle speed and the transaxle in the
NEUTRAL position. Make sure that all unused
vacuum outlets are correctly capped, hose
connectors are correctly secured and vacuum
hoses are in good condition. When it is
established that manifold vacuum is available
to the brake booster, connect the vacuum hose
to the brake booster and repeat Step 3. If no
downward movement of the brake pedal is felt,
install a new brake booster.
5. Operate the engine a minimum of 10 seconds at approximately 1200 rpm. Stop the engine and
let the vehicle stand for 10 minutes. Then, apply
the brake pedal with approximately 89 N (20 lb)
force. The pedal feel (brake application) should
be the same as that noted with the engine
operating. If the brake pedal feels hard (no
power assist), install a new vacuum check valve
and then repeat the test. If the brake pedal still
feels hard, install a new brake booster. If the
brake pedal movement feels spongy, bleed the
brake system. REFER to: (206-00 Brake System
- General Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General
Procedures),
Component Bleeding (General Procedures).
Brake Master Cylinder
Usually, the first and strongest indicator of anything
wrong with the braking system is a feeling through
the brake pedal. In diagnosing the condition of the
brake master cylinder, check pedal feel as
evidence of a brake concern. Check for the red
brake warning indicator illumination and the fluid
level in the master cylinder reservoir.
Normal Conditions
The following conditions are considered normal
and are not indications that the brake master
cylinder is in need of service.
– Modern brake systems are not designed to
produce as hard a pedal effort as in the past.
Complaints of light pedal efforts should be compared to pedal efforts of another vehicle, of
the same model and year.
– During normal operation of the brake pedal, the fluid level in the reservoir will rise during brake
pedal application and fall during release. The
net fluid level (i.e., after brake pedal application
and release) will remain unchanged.
– A trace of brake fluid will exists on the brake booster shell below the master cylinder
mounting flange. This results from the normal
lubricating action of the master cylinder bore
end seal.
– The fluid level will fall with brake shoe and lining wear.
Abnormal Conditions
NOTE: Prior to performing any diagnosis, make
sure the brake system warning indicator is
functional.
Changes in brake pedal feel or travel are indicators
that something could be wrong with the braking
system. The diagnostic procedure and techniques
use brake pedal feel, warning indicator illumination
and low brake fluid level as indicators in diagnosing
braking system concerns. The following conditions
are considered abnormal and indicate that the
brake master cylinder is in need of service.
– The brake pedal goes down fast. This could be caused by an external or internal leak.
– The brake pedal eases down slowly. This could be caused by an external or internal leak.
– The brake pedal is low and or feels spongy. This condition may be caused by no fluid in the brake
master cylinder reservoir, reservoir cap vent
holes clogged or air in the hydraulic system.
– The brake pedal effort is excessive. This may be caused by a bind or obstruction in the pedal
or linkage, clogged fluid control valve or
insufficient booster vacuum.
– The rear brakes lock up during light pedal force. This may be caused by incorrect tire pressures,
grease or fluid on the brake shoes and linings,
damaged brake shoes and linings, incorrectly
adjusted parking brake, or damaged or
contaminated brake pressure control valves.
– The brake pedal effort is erratic. This condition could be caused by a brake booster malfunction,
extreme caliper piston knock back or incorrectly
installed brake shoes and linings.
– The red brake warning indicator is ON. This may be caused by low fluid level, ignition wire routing
G1058975en2008.50 Kuga8/2011
206-00- 18
Brake System - General Information
206-00- 18
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Anti-Lock Control - Stability Assist – System Operation andComponent Description
System Diagram
E82694
M
P
UP
U
P
U
P
U
P
U
1
10
22
23
456
7
8
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1213
1415
1617
18
2324
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11
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19
2526
2120
181818
18
Description
Item
Brake booster
1
Primary hydraulic circuit
2
Secondary hydraulic circuit
3
Pulsation damper
4Description
Item
Pulsation damper
5
engine control module
6
Damping chamber
7
Dual circuit hydraulic pump
8
G1001304en2008.50 Kuga8/2011
206-09B- 7
Anti-Lock Control - Stability Assist
206-09B- 7
DESCRIPTION AND OPERATION
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Description
Item
Battery
1
Battery junction box (BJB) in the engine
compartment
2
Generic electronic module (GEM)
3
Powertrain Control Module (PCM)
4
Instrument cluster
5
Data link connector (DLC)
6
Steering Wheel Rotation Sensor
7
ABS/ESP module or hydraulic control unit
(HCU)
8Description
Item
Combined yaw rate sensor and lateral
acceleration sensor / longitudinal
acceleration sensor
9
Front wheel sensor
10
Rear wheel sensor
11
Rear wheel sensor
12
Front wheel sensor
13
ESP switch
14
Rear brakes
15
Front brake
16
The ABS monitors the different wheel speeds of
the vehicle with the aid of wheel speed sensors.
Using the data from all of the wheel speed sensors,
the ABS module calculates the so-called reference
speed, which is a measure of the actual road
speed. The ABS module compares the individual
circumferential wheel speeds with this reference
speed when the driver initiates braking. If one or
more of the circumferential wheel speeds deviates
too far from the reference speed, this means that
slip at the affected wheels is so great that steering
stability of the vehicle is no longer ensured. The
ABS module actuates electro-mechanical valves
which influence the brake pressure at the relevant
wheels.
Like the traction control system (TCS), the ESP
system uses a large proportion of the ABS
components. In addition, there are sensors which
pick up the steering angle, the acceleration forces
acting on the vehicle and the yaw rate or yaw
moment. The sensors transmit these signals to the
combined ABS/ESP module. Using the wheel
speed and steering angle data, the ABS/ESP
module calculates the direction of travel planned
by the driver and determines the corresponding
speed-dependent lateral acceleration and yaw
moment. These values are compared with those
actual measured. If the actual lateral acceleration
and the yaw moment deviate excessively from the
target values (unstable driving characteristics), the
ABS/ESP module actuates individual brakes
selectively via the HCU (hydraulic control unit). In
addition, the engine speed is reduced by
intervention in the engine management system.
How the system works for understeer: In the
event of understeer, brake intervention occurs at
the wheels on the inside of the curve. The rear
wheel is braked heavily, so that a high amount of slip is caused. In this way, the cornering force of
the rear axle is heavily reduced and the centrifugal
force that now becomes effective turns the rear of
the vehicle back into the curve. The front wheel is
not braked as hard. The braking force that is
transmitted via the front wheel to the road surface
generates a torque with the aid of the lever arm
(vertical tire force to the vehicle's centre of gravity),
which supports the yaw moment of the vehicle.
Both measures together result in the vehicle
reverting back to the curved path intended by the
driver.
How the system works for oversteer:
In the
event of oversteer the wheels on the outside of the
curve are braked. This time, the front wheel is
subjected to a high level of slip so that the
cornering force at the front axle is reduced. The
rear wheel is not braked as heavily and, together
with the effective lever arm, results in a reduction
in the vehicle yaw moment. Both measures
together result in the vehicle being stabilized and
reverting back to the curved path intended by the
driver.
If ESP control occurs, possible ABS interventions
will be overridden as the ESP works at higher slip
rates than the ABS.
Emergency brake assist (EBA): The emergency
brake assist helps drivers in emergency braking
situations by automatically applying the brakes with
the maximum possible braking force.
If the brake pedal is pressed very suddenly, the
ABS module increases the hydraulic pressure to
all of the brakes until the threshold for ABS
intervention is reached. This applies the maximum
braking effort for the available traction. The ABS
control unit monitors inputs from the brake pedal
switch and from the pressure sensor within the
G1001304en2008.50 Kuga8/2011
206-09B- 10
Anti-Lock Control - Stability Assist
206-09B- 10
DESCRIPTION AND OPERATION
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HCU to check for sudden actuation of the brakes.
With the brake pedal pressed, the ABS module
triggers emergency braking if the rate of increase
of hydraulic pressure exceeds the predetermined
limit.
If the brake pedal is pressed so hard that the ABS
becomes active on the front wheels then the ABS
control unit increases the pressure to the rear
wheel brakes up to the ABS intervention threshold.
EBA operation continues until the driver releases
the brake pedal sufficiently for the hydraulic
pressure in the HCU to drop below a threshold
value stored in the ABS module.
Trailer stability control:If the vehicle is ordered
with a trailer coupling then the Trailer Stability
Control function is integrated in the ESP. The ESP
detects snaking when driving with a trailer and
reduces the speed of the vehicle and trailer through
adapted braking and, if necessary, by also reducing
the engine output until the snaking movement of
the trailer is corrected.
Roll-over protection: The ESP dynamically
determines the tipping tendency of the vehicle and
works in conjunction with the EBA system to
prevent the vehicle from tipping over during
dynamic maneuvers like lane changing or while
negotiating bends.
Emergency brake light: The emergency brake
light automatically switches on the hazard flasher
system to warn drivers of other vehicles that
emergency braking is being initiated. Based on a
defined delay value, the ABS/ESP module sends
a signal to the generic electronic module (GEM)
via the CAN data bus. The GEM activates the
hazard flasher system, that then flashes 7 times.
Prerequisites for activation of the emergency brake
light are:
• The speed is higher than 50 km/h.
• The brake pedal is being actuated.
• The deceleration is greater than 9 m/s².
To prevent activation on snow or ice, for example,
the following prerequisites must be met:
• The speed is higher than 50 km/h.
• The brake pedal is being actuated.
• ABS regulation takes place.
• The deceleration is greater than 6 m/s².
Tire pressure monitoring system: The tire
pressure monitoring system used in the Kuga is
able to detect loss of air in a tire at an early stage
and warn the driver. Because it can only compare
the behaviour of the tyres with each other, it is not possible to draw conclusions about the absolute
tyre pressure. It is also not possible to monitor the
spare tyre pressure. In order for the system to
operate correctly, the tyre pressures must be
regularly checked and corrected and the system
subsequently initialised (see below).
The tire pressure monitoring system used here,
depending on the equipment level, is built into the
anti-lock braking system (ABS) as an extra function
and therefore does not have its own sensors.
The ABS module measures the loss of pressure
in the tyres by calculation using the wheel speed
sensors of the ABS system. If a tyre loses
pressure, its diameter decreases and the speed of
the wheel therefore increases. If the ABS module
detects such a loss in pressure, it sends a signal
to the instrument cluster via the CAN bus and a
warning message is displayed in the message
centre. The warning threshold depends among
other things on the dimension of the tyres being
used, the vehicle operating conditions and the
status at the last initialisation. Since neither the
absolute tyre pressure nor the position of the tyre
is known, the pressure of all the tyres must be
checked and the system re-initialised after a tyre
pressure warning. If necessary, the cause of the
loss of pressure must be investigated.
Regular tyre pressure checks are still necessary.
The system must be initialised after a tyre is
changed, winter or summer tyres fitted, the
pressures corrected or adjusted to suit the vehicle
load. This can be done by the driver using the
driver information system. For further information,
see: Owner’s Manual.
Component Description
Opto-electronic steering wheel rotation
sensor
E80158
G1001304en2008.50 Kuga8/2011
206-09B-
11
Anti-Lock Control - Stability Assist
206-09B- 11
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Description
Item
Electro-hydraulic power steering pump
with integrated power steering moduleRefer to Component Description:
Electro-hydraulic power steering pump
(page5)
1
Ignition switch
2
Generic electronic module (GEM)
3
Data link connector (DLC)
4
Powertrain Control Module (PCM)
5
ABS module or ESP module
6Description
Item
Steering gear
7
Integrated steering angle sensor - vehicles
built up to 09/2009RefertoComponentDescription:(page
10)
8
High pressure pipe
9
Fluid Return Line
10
Battery junction box (BJB)
11
Battery
12
System Operation
Electronic principle of operation
The power steering module requires the following
information in order to ensure precise steering
behavior in all driving situations:
• Steering wheel position
• Rate of turn of the steering wheel
• Vehicle speed
• Information about the vehicle configuration
• Information about the ignition switch position
• Instantaneous engine operating status
The required information is made available to the
power steering module via direct connections and
via the CAN bus (refer to the flow chart).
The steering wheel position and the rate of turn of
the steering wheel are transmitted to the power
steering module as PWM signals from the steering
angle sensor. The steering angle sensor receives
its voltage and ground supply from the power
steering module and operates inductively with an
input voltage of 5 V.
The vehicle speed is made available to the power
steering module as a CAN bus signal from the ABS
module or ESP module. The engine operating status is made available to
the power steering module as a CAN bus signal
from the PCM.
The power steering module obtains the vehicle
configuration information via the CAN bus from the
GEM. This information is required by the power
steering module in order to define the internal
characteristics of the power steering.
The power steering module obtains information
about the current ignition switch position via the
voltage input (terminal 15) of the ignition switch.
Whilst constantly monitoring the relevant input
signals the power steering module accesses stored
maps. With the aid of this information the pump
speed is matched to the current driving situation.
An electronic diagnosis of the electro-hydraulic
power steering can be performed with the aid of a
diagnostic tester via the DLC of the vehicle. For
additional information please refer to "Diagnosis
and Testing" in this section.
G1001270en2008.50 Kuga8/2011
211-02-
8
Power Steering
211-02- 8
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Hydraulic principle of operation
E96442
3
4
5
7
8
6
1
2
Description
Item
Reservoir
1
Valve unit
2
Steering rack and pinion
3
Flow control/pressure relief - return
4
Flow control/pressure relief valve
5Description
Item
Outlet of the power steering pump
6
Electro-hydraulic power steering pumpRefertoComponentDescription:(page
5)
7
Low pressure suction line
8
When the engine is started, the electro-hydraulic
power steering pump sucks in power steering fluid
from the reservoir. The fluid flows through the pump
and is discharged under high pressure from the
outlet. The high-pressure line carries the power
steering fluid to the servo valve.
If no steering effort is applied, there is no resistance
to the circulation of power steering fluid and the
supply pressure from the pump is very low. Only
minimal pressure is applied by the servo valve to
the two sides of the piston in the working cylinder.
When the steering wheel is turned in either
direction, the return flow of fluid to the reservoir is restricted by the servo valve, causing the pressure
to increase on the supply side. The power steering
fluid is directed by the servo valve to the
corresponding side of the piston in the working
cylinder, providing the power assistance required
to reduce the steering effort. The power steering
fluid which is displaced towards the low-pressure
side of the cylinder flows through the servo valve
and the return line back to the reservoir.
Component Description
Electro-hydraulic power steering pump
G1001270en2008.50 Kuga8/2011
211-02-
9
Power Steering
211-02- 9
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