2004 DAEWOO LACETTI light

4E1 – 2IREAR DISC BRAKES
DAEWOO V–121 BL4
pulsation and/or front end vibration during braking. Thick-
ness can be measured with a commercially available mi-
crometer and should be 10 mm(0.39 inch) or over.
Light scoring of the rotor surfaces is acceptable if it does
not exceed 0.40 mm (0.016 inch) in depth. Scoring mea-
surements can be made with a commercially available
brake micrometer.
Lateral runout cannot exceed 0.8 mm (0.03 inch). If lateral
runout exceeds the specification, make sure that there is
no dirt between the rotor and the hub and that hub–to–ro-
tor contact surfaces are smooth and free from burrs. Use
a commercially available dial indicator to check the lateral
runout according to the following procedure.
1. Position the shift lever in NEUTRAL and raise the
vehicle.2. To preserve wheel balance, mark the relative posi-
tions of the wheel and hub, and remove the rear
wheel.
3. Fasten the brake rotor to the wheel hub.
4. Mount a dial indicator on the brake caliper.
5. Place the indicator tip approximately 10 mm (0.39
inch) from the outer edge of the brake rotor, per-
pendicular to the disc and under slight preload. Ob-
serve the indicator gauge while rotating the rotor.
6. After measuring is completed, remove the dial indi-
cator and the wheel nuts.
7. If necessary, refinish the rotor with precision equip-
ment. Measure the runout again after refinishing. If
the runout exceeds 0.8 mm (0.03 inch) after refin-
ishing, the rotor should be replaced.
8. Align the marks that were made before wheel re-
moval, and install the rear wheel.
9. Lower the vehicle.

SECTION : 4E2
REAR DRUM BRAKES
TABLE OF CONTENTS
SPECIFICATIONS4E2–1 . . . . . . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specifications 4E2–1. . . . . . . . .
DIAGNOSIS4E2–1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lining Inspection 4E2–1. . . . . . . . . . . . . . . . . . . . . . . . .
Drums 4E2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE AND REPAIR4E2–3 . . . . . . . . . . . . . .
ON–VEHICLE SERVICE 4E2–3. . . . . . . . . . . . . . . . . . . .
Brake Adjustment 4E2–3. . . . . . . . . . . . . . . . . . . . . . . . Shoe and Lining 4E2–4. . . . . . . . . . . . . . . . . . . . . . . . .
Wheel Cylinder Assembly 4E2–7. . . . . . . . . . . . . . . . .
Backing Plate 4E2–8. . . . . . . . . . . . . . . . . . . . . . . . . . . .
UNIT REPAIR 4E2–10. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wheel Cylinder 4E2–10. . . . . . . . . . . . . . . . . . . . . . . . .
GENERAL DESCRIPTION AND SYSTEM
OPERATION4E2–12 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drum Brakes 4E2–12. . . . . . . . . . . . . . . . . . . . . . . . . . .
SPECIFICATIONS
FASTENER TIGHTENING SPECIFICATIONS
ApplicationNSmLb–FtLb–In
Brake Line1612–
Brake Wheel Hub/Backing Plate–to–Rear
Axle Nuts2821–
Wheel Cylinder–to–Backing Plate Bolt8–71
DIAGNOSIS
LINING INSPECTION
1. Raise and suitably support the vehicle.
2. Remove the wheel. Refer to Section 2E, Tires and
Wheels.
3. Release the parking brake.
4. Remove the drum. Refer to ” Drum” in this section.
5. Measure the lining thickness. The minimum lining
thickness is 0.5 mm (0.02 inch).
CAUTION : To avoid injury when servicing brake
parts, do not create dust by grinding or sanding the
brake linings or by cleaning the wheel brake parts
with a dry brush or with compressed air.
Important : Replace the shoe and lining assembly in axle
sets only.
6. Install the drum, if removed. Refer to ”One–Piece
Drum” or ”Two–Piece Drum” in this section.
7. Install the wheel, if removed. Refer to Section 2E,
Tires and Wheels.
8. Lower the vehicle.
DRUMS
Whenever brake drums are removed, they should be thor-
oughly cleaned and inspected to see if the drums are
cracked, scored, deeply grooved, or beyond the specified
out–of–round limit.
S A cracked drum is unsafe for further service and-
must be replaced. Do not attempt to weld a cracked
drum. Smooth out any slight scores.
S Heavy or extensive scoring will cause excessive
brake lining wear and may require refinishing the
drum braking surface.
S If the brake linings are slightly worn but are still re-
usable and the drum is grooved, polish the drum
with a fine emery cloth but do not refinish it. Elimi-
nating all grooves in the drum and smoothing the
ridges on the lining would remove too much metal
and lining. If left alone, the grooves and ridges
match, and satisfactory service can be obtained. If
the brake linings need to be replaced, refinish a
grooved drum. A grooved drum, used with a new

4E2 – 10IREAR DRUM BRAKES
DAEWOO V–121 BL4
UNIT REPAIR
WHEEL CYLINDER
Disassembly Procedure
1. Remove the wheel cylinder assembly from the
backing plate. Refer to ”Wheel Cylinder Assembly”
in this section.
2. Twist off the boots, the pistons, and the seals from
each end of the wheel cylinder.
3. Remove the spring assembly.
4. Remove the bleeder cap and the bleeder valve.
Assembly Procedure
1. Inspect the wheel cylinder bore and the pistons for
scoring, nicks, corrosion, and wear.
2. Use a crocus cloth to polish out light corrosion in
the wheel cylinder bore.
Important : If the bore will not clean up with a crocus cloth,
replace the assembly.
3. Clean all the parts in clean denatured alcohol or
brake fluid. Dry all the parts with unlubricated com-
pressed air and lubricate the new seals, the pis-
tons, and the wheel cylinder bore with clean brake
fluid before assembly.
4. Thinly coat all the parts except the dust caps with
brake cylinder fluid.
5. Fasten the bleeder valve and the cap to the wheel
cylinder.

4F – 8IANTILOCK BRAKE SYSTEM
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
31. Turn the ignition switch to LOCK for 10 sec-
onds.
2. Turn the ignition switch to ON and observe the
ABS indicator.
Does the indicator light for 4 seconds and then go
off?–Go to Step 5Go to Step 4
4Check the ABS indicator.
Did the ABS indicator turn on and stay on?–Go to ”ABS In-
dicator Lamp Il-
luminated
Constantly”Go to ”ABS In-
dicator Lamp
Inoperative”
51. Turn the ignition switch to LOCK for 10 sec-
onds.
2. Turn the ignition switch to ON and observe the
parking brake / EBD indicator.
Does the indicator light for 4 seconds and then go
off?–Go to Step 12Go to ”EBD
System Indica-
tor Lamp Inop-
erative”
61. Turn the ignition switch to LOCK.
2. Disconnect the EBCM harness connector.
3. Turn the ignition switch to ON.
4. Use a digital voltmeter (DVM) to measure the
voltage from ground to terminal 15, 17, and 18
of EBCM harness connector.
Is the voltage within the specified value on each ter-
minal?11–14 vGo to Step 7Go to ”Power
Supply to Con-
trol Module, No
DTCs Stored”
71. Turn the ignition switch to LOCK.
2. Use a DVM to measure the resistance from the
EBCM harness connector, terminals 16 and 19
to ground.
Is the resistance equal to the specified value?
0 WGo to Step 9Go to Step 8
8Repair the open in the circuit BLK and BLK/WHT
that failed.
Is the repair complete?–System OK–
9Use a DVM to measure the resistance between ter-
minal 11 of the EBCM harness connector and termi-
nal 12 of the Data Link Connector (DLC). Is the re-
sistance below the specified value?2 WGo to Step 10Go to Step 11
10Replace the ABS unit assembly.
Is the repair complete?–System OK–
11Repair the open or high resistance in circuit DK BLU
between terminal 11 of the EBCM harness connec-
tor and terminal 12 of the DLC jack.
Is the repair complete?–Go to Step 1–
12Perform the road test described above.
Are any DTCs set?–Go to the table
for the DTC–

ANTILOCK BRAKE SYSTEM 4F – 47
DAEWOO V–121 BL4
J3B14F10
EBCM
ORN/
BLK
LT BLULT B L U
BLK/ WHT
C201 C202
141
40
19
61
G1062
4
15A Ef13
6
C10211
S30114
C201C110
76
C202 11
DIAGNOSTIC TROUBLE CODE (DTC) C0161
ABS BRAKE SWITCH CIRCUIT MALFUNCTION
Circuit Description
When the brake pedal is depressed, the contacts on the
brake light switch close to illuminate the brake lights. Bat-
tery voltage is also applied to terminal 14 of the electronic
brake control module (EBCM), which signals the ABS con-
troller that the brakes are applied and ABS may be need-
ed. Without this, signals from a wheel speed sensor that
may indicate need for ABS intervention are questionable.
When the brake pedal is not depressed, the EBCM termi-
nal 14 is grounded through the brake lights.
Diagnosis
This procedure will check whether there is no output or
constant output from the brake light switch and will deter-
mine the cause as a faulty switch or a problem in the cir-
cuitry.
Cause(s)
S The ground connection or the positive connection at
the EBCM has failed.
S There is an open, short to ground, or short to posi-
tive in the vehicle wiring.S The brake light switch has failed.
Fail Action
The system records a DTC C0161. ABS and EBD opera-
tion is enabled and ABS / EBD warning lamp don’t turn on.
Test Description
The number(s) below refer to step(s) on the diagnostic
table.
1. This simple test will isolate the problem to the fuse–
brake light switch–splice 301 area or the splice
301–EBCM area.
3. This is the first step in identifying an open, a short
to ground, a short to voltage, or a faulty brake light
switch.
11. This step begins the process of finding an open, a
defective connector, or a faulty EBCM.
Diagnostic Aids
Inspect wiring and connectors carefully and thoroughly.
Failure to do so could result in misdiagnosis, causing part
replacement with reappearance of the malfunction.

4F – 48IANTILOCK BRAKE SYSTEM
DAEWOO V–121 BL4
DTC C0161 – ABS Brake Switch Circuit Malfunction
StepActionValue(s)YesNo
1Step on the brake pedal.
Do the brake lights come on at all?–Go to Step 3Go to Step 2
2Remove your foot from the brake pedal.
Do the lights stay on continuously?–Go to Step 8Go to Step 11
3Check fuse EF13 in the engine compartment fuse
block.
Is fuse EF13 blown?–Go to Step 4Go to Step 6
41. Replace fuse EF13.
2. Check the new fuse.
Does the new fuse blow?–Go to Step 5Go to Step 7
51. Repair the short to ground in the brake light
circuitry.
2. Install a new fuse EF13.
Is the repair complete?–System OK–
6Repair the open in the brake light switch circuit ORN/
BLK from terminal 6 of connector C102 at the engine
fuse block to the brake light switch and circuit LT
BLU from terminal 11 of splice S301.
Is the repair complete?–System OK–
7Check for functioning of the brake lights and the ABS
system.
Is the repair complete?–System OK–
8Check the brake light switch on the brake pedal.
Is the switch faulty?–Go to Step 9Go to Step 10
9Repair the brake light switch.
Is the repair complete?–System OK–
10Repair the short to positive in the circuit YEL be-
tween the brake light switch, splice S301, the brake
lights, the center high–mounted stoplamp, and the
ABS wiring harness connector at the EBCM terminal
14.
Is the repair complete?–System OK–
111. Disconnect the EBCM connector.
2. Use a digital voltmeter (DVM) to measure volt-
age between pins 14 and 19 of the ABS har-
ness connector at the EBCM.
3. Have an assistant step on the brake pedal.
Does the DVM indicate the specified value?11–14 vGo to Step 13Go to Step 12

ANTILOCK BRAKE SYSTEM 4F – 65
DAEWOO V–121 BL4
GENERAL DESCRIPTION AND SYSTEM
OPERATION
BASIC KNOWLEDGE REQUIRED
Before using this section, it is important that you have a ba-
sic knowledge of the following items. Without this knowl-
edge, it will be difficult to use the diagnostic procedures
contained in this section.
S Basic Electrical Circuits : You should understand
the basic theory of electricity and know the mean-
ing of voltage, current (amps), and resistance
(ohms). You should understand what happens in a
circuit with an open or shorted wire. You should be
able to read and understand a wiring diagram.
S Use of Circuit Testing Tools : You should know how
to use a test light and how to bypass components
to test circuits using fused jumper wires. You should
be familiar with a digital multimeter. You should be
able to measure voltage, resistance, and current,
and be familiar with the controls and how to use
them correctly.
ABS SYSTEM COMPONENTS
The ABS 5.3 Antilock Braking System (ABS) consists of
a conventional hydraulic brake system plus antilock com-
ponents. The conventional brake system includes a vacu-
um booster, master cylinder, front disc brakes, rear lead-
ing/trailing 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, the EBD indicator (which
is connected to the parking lamp) and the rear disk brakes.
See “ABS Component Locator” in this section for the gen-
eral layout of this system.
The hydraulic unit with the attached EBCM is located be-
tween the surge tank and the fire wall on the left side of the
vehicle.
The basic hydraulic unit configuration consists of hydraulic
check valves, two solenoid valves for each wheel, a hy-
draulic pump, two accumulators, and two damper. The hy-
draulic unit controls hydraulic pressure to the front calipers
and rear wheel cylinders by modulating hydraulic pressure
to prevent wheel lockup.
Nothing in the hydraulic unit or the EBCM is serviceable.
In the event of any failure, the entire ABS unit with at-
tached EBCM must be replaced. For more information, re-
fer to ”Base Braking Mode” and ”Antilock Braking Mode”
in this section.
BASE BRAKING MODE
The baseline braking mode of the ABS 5.3 system used
in this vehicle is a diagonal split system. In this system,
one master cylinder circuit supplies pressure to the right
front and the left rear brakes; the other circuit supplies
pressure to the left front and the right rear brakes. All
valves in the hydraulic modulator are in their normal, non–
energized positions as shown in the drawings found in
”ABS System Components” in this section.

ANTILOCK BRAKE SYSTEM 4F – 71
DAEWOO V–121 BL4
TIRES AND ABS/EBD
Replacement Tires
Tire size is important for proper performance of the ABS
system. Replacement tires should be the same size, load
range, and construction as the original tires. Replace tires
in axle sets and only with tires of the same tire perfor-
mance criteria (TPC) specification number. Use of any
other size or type may seriously affect the ABS operation.
TIRES AND ABS/EBD
Notice : There is no serviceable or removable EEPROM.
The EBCM must be replaced as an assembly.
The EBCM is attached to the hydraulic unit in the engine
compartment. The controlling element of ABS 5.3 is a mi-
croprocessor–based EBCM. Inputs to the system include
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 K of Data Link Connector (DLC) for service diagnostic
tools and assembly plant 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 sole-
noids to reduce brake pressure to the wheel approaching
lockup. Once the wheel regains traction, brake pressure
is increased until the wheel again begins to approach lock-
up. This 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 (except
the serial data link), and each output for proper operation.
If it detects any system malfunction, the EBCM will store
a DTC in nonvolatile memory (EEPROM) (DTCs will not
disappear if the battery is disconnected). Refer to ”Self
Diagnostics” in this section for more detailed information.
FRONT WHEEL SPEED SENSOR
The front wheel speed sensors are of a variable reluctance
type. Each sensor is attached to the steering knuckle,
close to a toothed ring. The result, as teeth pass by the
sensor, is an AC voltage with a frequency proportional to
the speed of the wheel. The magnitude of the voltage and
frequency increase with increasing speed. The sensor is
not repairable, nor is the air gap adjustable.
FRONT WHEEL SPEED SENSOR
RINGS
The toothed ring mentioned above is pressed onto the
wheel–side (outer) constant velocity joint. Each ring con-
tains 47 equally spaced teeth. Exercise care during ser-
vice procedures to avoid prying or contacting this ring. Ex-cessive contact may cause damage to one or more teeth.
If the ring is damaged, the wheel–side constant velocity
joint must be replaced.
REAR WHEEL SPEED SENSOR AND
RINGS
The rear wheel speed sensors operate in the same man-
ner as the front wheel speed sensors. They incorporate a
length of flexible harness with the connector attached to
the end of the harness. The rear wheel speed rings are in-
corporated into the hub assemblies and cannot be re-
placed separately, but require replacement of the rear
hub/bearing assembly.
VALUE RELAY AND PUMP MOTOR
RELAY
The valve relay and the motor pump relay are located in-
side the electronic brake control module (EBCM) and are
not replaceable. If one should fail, replace the EBCM.
WIRING HARNESS
The wiring harness is the mechanism by which the elec-
tronic brake control module (EBCM) is electrically con-
nected to power and to ground, to the wheel speed sen-
sors, the fuses, the switches, the indicators, and the serial
communications port. The components, considered part
of the wiring harness, are the wires that provide electrical
interconnection, and connectors (terminals, pins, con-
tacts, or lugs) that provide an electrical/mechanical inter-
face from the wire to a system component.
INDICATORS
The electronic brake control module (EBCM) continuously
monitors itself and the other ABS components. If the
EBCM detects a problem with the system, the amber ABS
indicator will light continuously to alert the driver to the
problem. An illuminated ABS indicator indicates that the
ABS system has detected a problem that affects the op-
eration of ABS. No antilock braking will be available. Nor-
mal, non–antilock brake performance will remain. In order
to regain ABS braking ability, the ABS must be serviced.
The red BRAKE indicator will be illuminated when the sys-
tem detects a low brake fluid level in the master cylinder
or when the parking brake switch is closed (the parking
brake is engaged) or EBD system is diabled.
WARNING : EBD INDICATOR LAMP WIRING IS CON-
NECTED TO THE PARKING BRAKE LAMP. IF THE
PARKING BRAKE LAMP IS TURNED ON WHEN YOU
DRIVING, CHECKING ON WHETHER THE PARKING
BRAKE LEVER IS ENAGED OR THE BRAKE FLUID
LEVEL IS LOW. IF THE SYSTEM HAS NO PROBLEM,
THE EBD SYSTEM IS WORKING IMPROPERLY. THE
EBD SYSTEM MUST BE SERVICED.