2003 DAEWOO MATIZ sensor

ANTILOCK BRAKE SYSTEM 4F–3
DAEWOO M-150 BL2
DESCRIPTION AND OPERATION
ABS SYSTEM COMPONENTS
The Antilock Braking System (ABS) consists of a con-
ventional hydraulic brake system plus antilock compo-
nents. The conventional brake system includes a
vacuum booster, master cylinder, front disc brakes, rear
drum brakes, interconnecting hydraulic brake pipes and
hoses, brake fluid level sensor and the BRAKE indicator.
The ABS components include a hydraulic unit, an elec-
tronic brake control module (EBCM), two system fuses,
four wheel speed sensors (one at each wheel), intercon-
necting wiring, the ABS indicator, and the rear drum
brake. See “ABS Component Locator” in this section for
the general layout of this system.
HYDRAULIC UNIT
The hydraulic unit with the attached EBCM is located
between the surge tank and the fire wall on the right side
of the vehicle. The basic hydraulic unit configuration
consists of return pump motor, return pump, four isola-
tion valves, four dump valves, two Low Pressure Accu-
mulators (LPA), two High Pressure Attenuators (HPA).
The hydraulic unit controls hydraulic pressure to the
front calipers and rear wheel cylinders by modulating hy-
draulic pressure to prevent wheel lockup.
Isolation valve
The isolation valve is placed in the brake fluid path from
the master cylinder to the relevant brake caliper and al-
lows free flow as commanded by the driver during nor-
mal braking and reapply phases.
In the isolation phase the coil moves the armature down,
which closes the normally open isolation orifice and pre-
vents any further increase of pressure in the brake. The
valve also remains closed during the dump phase.
The lip seal provides a one way return path for brake
fluid to flow through in:
1. Foot off pedal during isolation.
2. Residual LPA fluid.
D107E002
Dump Valve
The dump valve creates a flow path from the isolation
cartridge (brake side) to the low pressure accumulator
(LPA). The valve keeps this path permanently closed ex-
cept during the dump phase in the ABS mode. On ac-
tivation (dump phase), the coil moves up the armature
which opens the normally closed dump orifice and allow
to drain the pressure in the brake line with the brake fluid
flowing into the LPA.
The lip seal provides a return path for residual brake
fluid in the LPA.
D107E003
Low Pressure Accumulator (LPA)
LPA provides a variable chamber for brake fluid to be
quickly pushed in through the dump valve at the begin-
ning of a departure. This chamber then acts as a reser-
voir which buffers the pump.
D107E004
High Pressure Attenuator (HPA)
The HPA is in between the pump and the ISO valve
(master cylinder side) and uses the bulk mode of the
contained plastic damper and orifice size to dump out
the pressure oscillations from the pump to reduce the

4F–4 ANTILOCK BRAKE SYSTEM
DAEWOO M-150 BL2
feed back to the master cylinder and brake pedal.
D107E005
Return Pump Motor
The motor drives two pump elements through the ec-
centric wheel on its shaft.
Return Pump
Description: Each pump element consists of a fixed
displacement piston driven by an eccentric on the end of
the eccentric motor. It has two check valves (inlet and
outlet) and is fed with fluid by the low pressure accumu-
lator.
Operation:
Compression stroke: the pump is filled via the inlet ball
seat, then the motor eccentric rotates moving the piston
to displace the fluid. After the pressure build-up closes
the inlet valve the piston displacement increases the
pressure until the outlet ball opens. The outlet pressure
will continue to increase for the rest of the piston stroke.
Return Stroke: The piston retracts, forced by its spring,
as the motor eccentric returns to its low end position.
The pressure at the inlet side of the outlet ball then de-
creases due to the displaced volume and the pressure
difference across this ball holds it closed.
The pressure at the outlet side of the inlet ball seat,
which is set to open at a certain pressure level also de-
creases until this valve opens. With the outlet ball
closed, the pump is filled with additional fluid from the
low pressure accumulator.
The pressure will continue until a stall point is reached
and compression of the piston cannot generate enough
differential pressure anymore to open the outlet ball
seat.
D17E006A
Return Pump
Return Pump
Motor(0.12~0.16 in.)
EBCM (ELECTRONIC BRAKE
CONTROL MODULE)
Notice: There is no serviceable. The EBCM must be re-
placed as an assembly.
The EBCM is attached to the hydraulic unit in the engine
compartment. The controlling element of ABS is a mi-
croprocessor-based EBCM. Inputs to the system in-
clude the four wheel speed sensors, the stoplamp
switch, the ignition switch, and the unswitched battery
voltage. There is an output to a bi-directional serial data
link, located in pin M of the assembly line diagnostic link
(ALDL), for service diagnostic tools and assembly plat
testing.
The EBCM monitors the speed of each wheel. If any
wheel begins to approach lockup and the brake switch is
closed (brake pedal depressed), the EBCM controls the
dump valve to reduce brake pressure to the wheel ap-
proaching lockup. Once the wheel regains traction,
brake pressure is increased until the wheel again begins
to approach lockup. The cycle repeats until either the
vehicle comes to a stop, the brake pedal is released or
no wheels approach lockup.
Additionally, the EBCM monitors itself, each input (ex-
cept the serial data link), and each output for proper op-
eration. If it detects any system malfunction, the EBCM
will store a DTC in nonvolatile memory (DTCs will not
disappear if the battery is disconnected).

ANTILOCK BRAKE SYSTEM 4F–5
DAEWOO M-150 BL2
D107E001
WHEEL SPEED SENSORS AND
RINGS
Front wheel speed sensors are installed to the front
knuckle and rear wheel speed sensors are installed to
the backing plate.
Wheel speed sensors are no serviceable. And the air
cap is not adjusted. Front wheel speed sensor ring is
pressed onto the drive axle shaft. Each ring contains 40
equally spaced teeth. Exercise care during service pro-
cedures to avoid prying or contacting this ring. Exces-
sive contact may cause damage to one or more teeth.
Rear wheel speed sensor rings are incorporated into the
hub drum.
D107E007
D107E008
ELECTRONIC BRAKE DISTRIBUTION
ABS features an enhanced algorithm which includes
control of the brake force distribution between the front
and rear axles. This is called Electronic Brake Distribu-
tion or Dynamic Rear Proportioning valve. In an unladen
car condition the brake efficiency is comparable to the
conventional system but for a fully loaden vehicle the ef-
ficiency of the Dynamic Rear Proportioning System is
higher due to the better use of rear axle braking capabili-
ty.
No indication is given to the driver when Dynamic Rear
Proportioning is activated. Also, DRP remains active
even in such cases where the anti-lock function of the
ABS is disabled.
D17E009A
Critical Brake Points
Ideal Distribution
Fully Laden Vehicle
Ideal Distribution
Lightly Loaded
Vehicle
Advanced Distribution with ABS
Regular Distribution without Dynamic
Rear Proportioning
Relative Front Brake Force
INDICATOR
It illuminates for four seconds immediately after the igni-
tion has been turned on to show that the anti-lock sys-
tem self-test is being carried out. If the light does not go
off after this time it means that there may be a problem
and ABS operation is not available.
If any malfunction or error, including an unplugged
EBCM connector, is detected during vehicle operation,
the light will come on, warning the driver that the ABS is
not operative and brake operation is in conventional,
non-ABS mode.
D17E010A

4F–8 ANTILOCK BRAKE SYSTEM
DAEWOO M-150 BL2
Master Cylinder
High Pressure Attenuator
High Pressure Attenuator
Return Pump Motor
Return Pump Return Pump
Low
Pressure
Accumulator
Low Pressure
Accumulator
RRFL FR
RL
D17E206A
RR
Isolation ValveFL
Isolation Valve
RR Dump ValveFL
Dump
ValveFR
Isolation Valve
FR Dump ValveRL
Dump
ValveRL
Isolation
Valve
ISOLATION MODE (PRESSURE MAINTAIN)
If the information from the wheel speed sensors indicate excessive wheel deceleration (imminent lockup), the first step
in the antilock sequence is to isolate the brake pressure being applied by the driver. The EBCM sends a voltage to the
coil to energize and close the isolation valves by pulling down on the armature. This prevents any additional fluid pres-
sure applied by the driver from reaching the wheel. Though each channel of the 4-channel system can operate inde-
pendently, once any front channel (brake) sees excessive deceleration, both front isolation valves are energized and
close thus, with the isolation valves closed, further unnecessary increases in the brake pressure will be prohibited.

ANTILOCK BRAKE SYSTEM 4F–11
DAEWOO M-150 BL2
Master Cylinder
High Pressure Attenuator
High Pressure Attenuator
Return Pump Motor
Return Pump Return Pump
Low Pressure
Accumulator
RRFL FR
RL
D17E209A
RR
Isolation Valve
Low
Pressure
AccumulatorFL
Isolation Valve
RR Dump ValveFL
Dump
ValveFR
Isolation Valve
FR Dump ValveRL
Dump
ValveRL
Isolation
Valve
PROPORTIONING FUNCTION
If the rear wheels lock formerly during braking, the vehicle may lose the stability. Therefore to prevent this, the ECM
processes the speed sensor signal and brake signal to determine when the rear wheels are tending to lock up. The
EBCM then actuates the rear wheel isolation valves to reduce the rear brake pressure and keep the wheels rolling.

ANTILOCK BRAKE SYSTEM 4F–13
DAEWOO M-150 BL2
COMPONENT LOCATOR
ABS
D17E401A
1. Hydraulic Modulator Unit
2. Electronic Brake Control Module (EBCM)
3. Bolt
4. Upper Mounting Bracket
5. Grommet6. Lower Mounting Bracket
7. Bracket Grommet
8. Rear Wheel Speed Sensor
9. Front Wheel Speed Sensor

4F–16 ANTILOCK BRAKE SYSTEM
DAEWOO M-150 BL2
DIAGNOSTIC INFORMATION AND PROCEDURES
D17E301A
DIAGNOSTIC TROUBLE CODE (DTC) 0354
LEFT FRONT WHEEL SPEED SENSOR CIRCUIT OPEN OR SHORTED
Circuit Description
As a toothed ring passes by the wheel speed sensor,
changes in the electromagnetic field cause the wheel
speed sensor to produce a sinusoidal (AC) voltage sig-
nal whose frequency is proportional to the wheel speed.
The magnitude of this signal is directly related to wheel
speed and the proximity of the wheel speed sensor to
the toothed ring often referred to as the air gap.
Diagnosis
This test detects a short to battery, ground, or open in
the left front wheel speed sensor circuit.
Cause(s)

The wheel speed circuit is open or shorted to the bat-
tery or ground.

There is a loose connection in the wheel speed cir-
cuit.

The wheel speed sensor resistance is very high.

The EBCM is malfunctioning.Fail Action
This is a critical operational fault. The ABS is disabled
and the ABS warning lamp is turned on. The proportion-
ing is operation.
Diagnostic Aids
An ‘‘intermittent’’ malfunction may be caused by a poor
connection, rubbed through wire insulation, or a wire
that is broken inside the insulation.
Thoroughly check any circuitry suspected of causing the
intermittent complaint. Look for backed out terminals,
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal to wiring connections,
or physical damage to the wiring harness.
Wheel speed sensor resistance will increase as the sen-
sor temperature increases.
When replacing a wheel speed sensor, inspect the sen-
sor terminals and harness connector for corrosion and/
or water intrusion. If evidence of corrosion or water

ANTILOCK BRAKE SYSTEM 4F–17
DAEWOO M-150 BL2
intrusion exists, replace the wheel speed sensor har-
ness. If replacing a wheel speed sensor harness, in-
spect the sensor terminals. If you find evidence of
corrosion or water intrusion, replace the wheel speed
sensor. Refer to “Front Wheel Speed Sensor” in this
section.Important: Wheel speed sensor intermittent malfunc-
tions may be difficult to locate. Take care not to disturb
any electrical connections before performing an indi-
cated step of this table. That will ensure that an intermit-
tent connection will not be corrected before the source
of the malfunction is found.
DTC 0354 – Left Front Wheel Speed Sensor Circuit Open or Shorted
 Step Action Value(s) Yes No
 
 
 
 
 
 
 
1
 
 
 
 
 
 
 
1. Turn the ignition switch to OFF.
2. Disconnect the EBCM harness connector from
the EBCM.
3. Use a digital voltmeter (DVM) to measure the
resistance between terminals 14 and 25 of
connector on the EBCM harness.
Is the resistance within the specified value? 
 
 
 
 
 
 
1.0 k
to
1.5 k

 
 
 
 
 
 
 
Go to Step 4
 
 
 
 
 
 
 
Go to Step 2
 
 
 
 
 
2
 
 
 
 
 
1. Disconnect the harness from the left front wheel
speed sensor.
2. Use a DVM to measure the resistance between
terminals 1 and 2 of the left front wheel speed
sensor connector.
Is the resistance within the specified value? 
 
 
 
 1.0 k
to
1.5 k

 
 
 
 
 Go to Step 4
 
 
 
 
 Go to Step 3
 
 3
 
 Replace the wheel speed sensor.
Is the repair complete?
 
 –
 
 System OK
 
 –
 
 
 
 
4
 
 
 
 
Use a DVM to measure the resistance between ter-
minal 14 of the EBCM harness connector, and termi-
nal 1 of the left front wheel speed sensor harness
connector.
Is the resistance within the specified value? 
 
 
 
less than 1

 
 
 
 
Go to Step 6
 
 
 
 
Go to Step 5 
 
 
 
5
 
 
 
 
1. Repair the high resistance in circuit DK BLU.
2. If the wheel speed sensor harness is damaged,
replace it.
Is the repair complete?
 
 
 
 
–
 
 
 
 System OK
 
 
 
 
–
 
 
 
 
6
 
 
 
 
Use a DVM to measure the resistance between ter-
minal 25 of the EBCM harness connector, and termi-
nal 2 of the left front wheel speed sensor harness
connector.
Is the resistance within the specified value? 
 
 
 less than 1

 
 
 
 Go to Step 8
 
 
 
 Go to Step 7 
 
 
 
7
 
 
 
 
1. Repair the high resistance in circuit YEL.
2. If the wheel speed sensor harness is damaged,
replace it.
Is the repair complete? 
 
 
 
–
 
 
 
 System OK
 
 
 
 
–
 
 8
 
 
Use a DVM to measure the resistance between
ground and terminal 14 of the EBCM connector.
Does the DVM show the specified value? 
 

 
 Go to Step 10
 
 Go to Step 9 
 9
 
 Repair the short to ground in circuit DK BLU.
Is the repair complete? 
 –
 
 System OK
 
 –