sensor GREAT WALL FLORID 2008 User Guide

Downloaded from www.Manualslib.com manuals search engine 95Brake System
Brake System Components Arrangement Schematics
Brake pedal assembly
Vacuum booster with brake cylinder assembly
Left steering knuckle and hub brake assembly
Left parking brake cable assembly
Rear brake assembly RHRear brake drum
Rear wheel speed sensor assembly RH
Right parking brake cable assembly
ABS controller assembly
Right steering knuckle and hub brake assembly
Brake line assembly
Rear wheel speed
sensor assembly LH
Front wheel speed sensor assembly RHFront wheel speed sensor assembly LH
Rear brake assembly LH
Parking brake control mechanism assembly

Downloaded from www.Manualslib.com manuals search engine 107Brake System
Anti-lock Brake System
ABS/EBD introduction
1. Operation
The vehicle's Anti-lock Brake System (ABS) is a type of increasingly popular brake safety device. It detects the
wheel's speed using wheel speed sensor detection. After signal processing, the wheel speed will be transferred
to the computer, which controls the solenoid valve’s operating condition and the pressure inside the brake wheel
cylinder to avoid wheel locking by using certain calculations and control methods based on the wheel speed.
ABS helps the vehicle to avoid sliding, deviation, fishtailing, and losing steering control capacity. ABS improves
the vehicle’s handling capability, stability and shortens braking distance. It also helps the vehicle to avoid the
partial wear and tear of wheels, hence improves the tire's useful life.
Electronic Brake Distribution (EBD) is used to adjust the vehicle's rear wheel brake pressure by using the ABS
components when the ABS does not respond to vehicle braking. It is also used to balance the vehicle’s front and
rear wheel brake pressure, maximizing the vehicle's braking efficiency. EBD uses the ABS components, yet its
controlling logic is independent from the ABS. After the ABS responds, the EBD will disengage.
2. Basic structure
3. ABS working process
(a) Pressure rising phase: While service braking, oil pressure output from the pump passes the inlet solenoid
valve and enters the brake wheel cylinder. The brake generates braking force and the wheel speed sharply
declines until the ABS control unit detects that the wheel is starting to lock via the wheel speed sensor
detection.
(b) Pressure maintaining phase: When the ABS control unit detects that the wheel is starting to lock via wheel
speed sensor signal, the inlet solenoid valve closes, with the outlet solenoid valve shut as usual. The
pressure maintaining phase thus begins.
(c) Pressure drop phrase: During the pressure maintaining phase, the wheels tend to lock further. This brings
the ABS into the pressure drop phrase. With the inlet valve closed and the outlet valve open, the hydraulic
pump starts working, and brake fluid returns to the brake pump from the wheel cylinder by passing through
the low pressure accumulator. The brake pressure reduces and the brake pedal bounces back.
(d) Pressure maintaining phase: With the degree of wheel locking decreases and wheel speed begins to
increase, the pressure maintaining phrase begins.
(e) Next cycle’s pressure rising phase: When the wheels reach a certain speed, the ABS enters the pressure rise
phase and starts the next cycle.
Note: The ABS's pressure adjusting frequency is generally 2 to 4 cycles per second.
ABS control unit
Wheel speed sensor
Wheel speed signal
Wheel cylinder
Valve work instruction
Hydraulic modulator
Vacuum booster & master cylinder

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4. EBD working process
The EBD comes into effect when the wheel brakes are lightly applied. The wheel speed sensor detects the speed
of the wheels, and the ECU calculates the speed. If the rear wheel's slip ratio increases, adjust the brake pressure
to maintain or reduce the rear wheel's braking force. The EBD guarantees the rear wheel's lateral force and even
brake force distribution. If the ABS fails to respond, the electronic brake distribution system can still adjust the
rear wheel's braking force to guarantee the rear wheels do not lock before the front wheels, in order to ensure
vehicle safety.
The EBD's working process for lifting and holding pressure is completely the same as it of the ABS working
process. However, the process for lowering pressure is quite different. When the rear wheel has a tendency to
lock up, the normally open valve of the rear wheel closes, the normally closed valve opens, and the rear wheel
pressure reduces. The difference with ABS is that the hydraulic pump does not operate at this time, and the brake
fluid released during depressurization is temporarily stored in the low pressure accumulator. After braking,the brake
pedal is loosened, and the brake pressure inside the pump drops to zero. Open the normally closed valve one more
time at this point. The brake fluid inside the low pressure accumulator returns to the pump by passing through the
normally closed valve and normally open valve. Empty the low pressure ac\
cumulator to prepare for the next brake.
ABS installation
1. Install the ABS controller assembly.
(a) Use three hexagon bolts for flange face (Q1840825) to
fix the ABS bracket assembly onto the vehicle body.
(b) Fix the shock pad of the ABS hydraulic pump onto the
mounting holes of the ABS bracket assembly.
(c) Insert the mount pin of the ABS controller assembly
into the shock pad holes by simply inserting the two
anchor pins into the bracket.
2. Install the ABS front wheel speed sensor with bracket
assembly.
(a) Use a hexagon head bolt, spring washer, and flat
washer subassembly to connect the sensor and the
steering knuckle.
(b) Use a hexagon head bolt and a flat washer subassembly
(M8) to connect the sensor bracket and the damper.
(c) Use a hexagon head bolt and a flat washer subassembly
(M6) to connect the sensor bracket and vehicle body.
ABS controller assembly
ABS hydraulic pressure pump shock pad
ABS mounting bracket assembly
Wheel speed sensor with bracket assembly
Steering knuckle
Propeller shaft
Wheel slippage
Vehicle speed
Wheel speed
Master cylinder pressure
Wheel cylinder brake pressure

Downloaded from www.Manualslib.com manuals search engine 109Brake System
3. Installing the ABS rear wheel speed sensor with brack-
et assembly.
Use three hexagon head bolts, spring washers, and flat
washer subassembly connecting pieces to connect the sensor
to the rear hub unit, rear twist beam, and vehicle body.
ABS General Problem Maintenance and Areas of Importance
Common problems and solutions
1. When braking, the ABS hydraulic pressure unit noise is overly loud.
When the ABS is working, the motor inside the hydraulic pressure unit is ceaselessly rotating. At this time the
driver can feel the brake pedal bouncing back. However, this bounce back feeling will be entirely different
depending on the speed and road condition. Also, when performing an actuator movement test, the sound of the
running motor may also be sensed. When the vehicle is being driven and the brake is off, the sound of the motor
running can still occasionally be heard. This is the ABS undergoing component inspection, not a malfunction.
If the ABS hydraulic pressure unit noise is irregular, a movement test can be initiated. Compare the noise to that
of normal vehicles to determine if ABS hydraulic pressure unit noise is abnormal.
2. Inlet and outlet solenoid valve failure.
Once the ignition switch is ON, the ABS control unit automatically initiates a self-check. If an inlet and outlet solenoid
valve short circuit or open circuit is found, it will record the failure, light up the fault light, and abort the operation. If using a
scanner to adjust the problem code, make sure to use the movement test t\
o confirm that the solenoid valve has a problem and
then replace the hydraulic pressure unit directly.
X431 data flow: While the ABS is functioning, the inlet and outlet solenoid valves rapidly change operating
conditions.
EVFL - Front inlet valve LHOff / On
AVFL - Front outlet valve LHOff / On
EVFR - Front outlet valve RHOff / On
AVFR - Rront outlet valve RHOff / On
EVRR - Rear inlet valve LHOff / On
AVRR - Rear outlet valve LHOff / On
EVRR - Rear inlet valve RHOff / On
AVRR - Rear outlet valve RHOff / On
3. Wheel speed sensor malfunction.
With the engine running, use a oscilloscope to measure the voltage between the sensor's signal line and the
ground.
Output signal when wheel is stationary:
Output signal when the wheels are rotating: signal type is 0.44 V and 1.26 V square wave signal, duty cycle: 50: 50.
Rear hub unit assembly
Rear wheel speed sensor with bracket assembly
Hexagon head bolt, spring washer, and flat washer subassembly
Hexagon head bolt, spring washer, and flat washer subassembly
0
v
t
vv
0 0
tt
or

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The X431 scanner possesses a waveform function. Wheel speed signal error (wheel speed sensor failure)
only appears when intermittent problems occure, such as high speed. When in use, some signal errors may
occasionally appear. Continue observing the waveform to make sure there is nothing abnormal.When driving
the vehicle on a flat and straight road, all four wheels' speed sensor waveform are extremely similar. One can
compare the two front wheels' with the two rear wheels' signal wave at t\
he same time.
Mechanical causes:
Signal gear distortion, loosened hub bearings, smudges on the sensor surface, etc, all may lead to wheel speed
signal intermittency and inaccuracy. Failure examples:
As shown above, once the intermittent failures with the wheel's speed sensor signal are detected, the ABS
control unit records the sensor problems and lights up the warning lamp.\
4. Wheel speed sensor velocity failure (ECU detects an excessive difference between the two wheels'
speed sensor signals).
Possible causes are the gear's wheel speed sensor gap is overly large, or the wheel speed sensor signal is
experiencing interference. For this, first determine which sensor is emitting the signal, and then use failure
three's maintenance methods.
Areas of Importance
1. Sometimes, in order to determine whether there is a common brake system problem or an ABS
problem, the ABS must be terminated by pulling out its ABSECU connector or fuse. At this time the
ABS/EBD loses function as well. On muddy, icy, or snowy roads, the vehicle may fishtail or slide, in
which cases one must be extremely careful to avoid hard braking.
2. The ABS malfunction rate is extremely low, when the brake system shows any problem (before the
warning lamp goes on), first eliminate the normal brake system problems, then consider the ABS mal-
functions.
3. When raining or on gravel, this adjusting process is longer than the standard process, because this
kind of road's unstable adhesion coefficient will lead to a difference between the sliding measurement
and calculation procedures, thus it is necessary to remind drivers to be especially careful when driving
under the circumstances mentioned above.
4. ABSECU Areas of Importance:
(a) The ABSECU is easily damaged from impacts or collisions, thus pay attention to ensure the ECU avoids
such incidents.
(b) High temperature environments can also easily damage the ECU, so when the vehicle undergoes hot paint
work, make sure to first take the ECU out of the vehicle.
(c) When the power switch is ON, do not disassemble the system's electrical elements and wire harness plugs,
in order to avoid damage to the ECU. If removal or installation must be carried out, be sure to disconnect
the ignition switch firstly. When welding components or circuits to the system, the wire harness plug
V( Km/h)
60
30
Signal interrupt
t

Downloaded from www.Manualslib.com manuals search engine 111Brake System
ABS trouble code list
Trouble codeFault description
C0035Front wheel speed sensor LH circuit failure, velocity failure
C0040Front wheel speed sensor RH circuit failure, velocity failure
C0045Rear wheel speed sensor LH circuit failure, velocity failure
C0050Rear wheel speed sensor RH circuit failure, velocity failure
C0060Front ABS outlet solenoid valve LH failure
C0065Front ABS inlet solenoid valve LH failure
C0070Front ABS outlet solenoid valve RH failure
C0075Front ABS inlet solenoid valve RH failure
C0080Rear ABS outlet solenoid valve LH failure
C0085Rear ABS inlet solenoid valve LH failure
C0090Rear ABS outlet solenoid valve RH failure
C0095Rear ABS inlet solenoid valve RH failure
C0110Pump motor circuit failure, operational error
C0121Solenoid valve relay circuit failure
C0161Brake switch circuit failure
C0245Wheel speed sensor frequency error, wheel speed sensor signal failure
C0287Acceleration sensor failure
C0550ECU failure
C0800Voltage fault, voltage too high or too low
C0232Warning lamp positive short circuit, warning lamp ground short circuit
should also be removed from the ECU.
(d) Do not let oil contaminate the ECU. Be especially careful of the ECU terminals, otherwise it might obstruct
the connection among terminals of the wire harness plug.
Note: The BOSCH ABS8.0 hydraulic pressure unit (integrated into the ECU) is not serviceable. If
damaged, the whole unit must be replaced.

Downloaded from www.Manualslib.com manuals search engine GWFLORID Maintenance Manual144
Double-colored wire: Primary color is Red, secondary color is Blue, mark\
ed as RBl.
0.5BrGr means Brown wire with a Gray fine wire, and sectional area is 0.\
5 mm2.
Areas of importance in circuit maintenance
1. Before operating any electronic devices, and when tools or maintenance devices may easily make
contact with an uncovered electronic terminal, please make sure to turn the ignition switch to the LOCK
position, and then disconnect the battery's negative cable to avoid injury or vehicle damage. When the
ignition switch is on the ON position, please do not disconnect the battery's connecting wire or take out
the power's fuse, regardless if the engine is running or not.Otherwise it would seriously damage the
ECU and related microelectronic devices such as sensors.
2. When changing the fuse, please make sure that the new fuse possesses the proper current rating,
and is not above or below this rating.
3. When repairing the wire harnesses of the airbag and pretensioner, only specified contact points,
plugs, and wires are allowed to be used.
4. Before repairing the wire harness, make sure to eliminate any factor that might cause damage,
for example, the edge of a vehicle body part is too sharp, or the used electronics are damaged or
corroded.
5. Shielded wire should not be repaired, it must be replaced entirely once it is damaged.
6. Unless it is specified during the test, please do not use an analog multimeter to test the ECU and
sensor, instead use a high-impedance digital multimeter (internal resistance should be ≥10 kΩ) or a
vehicle multimeter for inspection.
7. When inspecting the connector with a digital multimeter, take the waterproof rubber cover off the
connector, and tightly insert the test pen along the connecting terminal. Don't use too much force, as
to avoid cracking the connector.
Circuit inspection steps
The principle of troubleshooting is to confirm the "possible cause". Once the possible cause is confirmed, the
components that need to be inspected are limited to the components that are related to the possible cause. The
confirmed possible cause should be based on theory and be supported by facts, but not just by intuition. If
one tries to solve the problem but does not adopt the proper troubleshooting steps, it may make the problem
worse. Then the possible cause not only can't be confirmed, but also maintenance can't be performed properly.
Troubleshooting should adhere to the four steps below:
1. Observe the symptoms carefully, inspect if there is anything else abnormal, and record it.
2. While confirming the possible causes, study the circuit diagram carefully, and regard it as a whole
system in order to understand the circuit. Thorough knowledge of switches, relays, and other
electronic components is obligatory for proper analysis.
3. Inspect and eliminate the problems one by one until the cause is found.
4. After the malfunction is fixed, make sure to check if the inspected system is working properly, and also
check if the maintenance may have caused any new problems.
Compres-
sor relay
Reserve
Sunroof (Elite) Lamplet
Reserve
Reserve
Reserve
Reserve Door and window Reserve Blower
Lamplet
relay Flasher relay Blower high
speed relay (Elite) Door and
window relay (Comfort, Luxury) Blower relay
Reserve
Front fog lamp
Combination
meter
Interior
lighting
central
door lock
brake lamp
CD player
Reserve
Reserve
Reserve
Cigarette
lighter
Rearview
mirror
Front wiper
Charge
Airbag
Reserve
Reverse lamp Rear fog lamp
Rear wiper
Defroster Compressor
ACC relay
IG relayRear wiper
relay Defroster
relay
Front fog
lamp relay Rear fog
lamp relay
Warning lamp
Turn signal lamp
Cab No.1 fuse box
Fuse Box

Downloaded from www.Manualslib.com manuals search engine GWFLORID Maintenance Manual152
Engine ECUInjector
Starter, starter excitation, knock sensor
Speed sensor
Brake switch
Brake fluid level switch
Clutch switch
ABS ECU
Front wiper
motor
Front combination lamp LH
Front fog lamp LH
Radiator fan
High & low pitched horn
Crankshaft position sensorFront & rear oxygen sensor
Condenser fan motor
Compressor clutch
Alternator, alternator regulator
Tristate pressure switch
Front fog lamp RH
Washer motor
Wheel speed sensor
Front combination lamp RH
Camshaft position sensor
Throttle position sensor
Wire Harness Distribution Chart for the Overall Vehicle
Engine compartment wire harness
ABS ECU
Positive fuse box
No. 2 fuse box
Reverse sensor ECU
Key Electrical Component’s Module Schematics for the Overall
Vehicle (Continued)

Downloaded from www.Manualslib.com manuals search engine 153Vehicle Body Electronic System
High mounted brake lamp
Rear defroster positiveRear wiper motor
Trunk lock motor, door lamp switch
Opener switchRear defroster negative
Theft deterrent indicator lampCombination meter CD/DVD
Air conditioner speed adjuster, AC switch, rear defroster switch
Air conditioner temperature sensorF r o n t P a s s e n g e r s i d e airbag assembly
BlowerGlove box lighting
Cigarette lighter and lighting
Airbag ECU assembly 2
Diagnostic port
Acceleration pedal
Power rearview mirror switch, light brightness regulator
Trunk door wire harness
Central lock controller
Dashboard wire harness

Downloaded from www.Manualslib.com manuals search engine GWFLORID Maintenance Manual154
Door lock motorDoor and window main switchesMiddle & low tone speaker
High tone speaker
Outer power rearview mirror
Window regulator motor
Door lock motor
Wi n d o w r e g u l a t o r switch
Window regulator motorMiddle & low tone speaker
Fog lampLicense plate lamp
Rear
combination lamp LH
Rear combination lamp RH
Rear wheel speed sensor RHParking brake switch
Front door light switch LH
Seat belt pretensioner
Rear wheel speed sensor LH
Rear door light switch LH
Backup power supply
Front & rear door wire harnesses
Vehicle body wire harness
Front doorRear door
Reverse sensor ECU
Reverse sensor probeOil pump motor