2004 DAEWOO LACETTI warning

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 – 50IANTILOCK BRAKE SYSTEM
DAEWOO V–121 BL4
J3B14F11
Left Front Left RearRight Front
Right Rear
EBCM
BRN LT
BLU1
2
6
7
PPL
GRYGRY GRY
YEL
C111
WHT 1
12
2
44
55WHT WHT1
1 2
43
89
Wheel Speed Sensors
BRNBRN DK
BLUBLK
BLK REDC302
C110 WHT
WHT1 2
2
110
33
DIAGNOSTIC TROUBLE CODE (DTC) C0245
WHEEL SPEED SENSOR FREQUENCY ERROR
Circuit Description
The toothed wheel generates a voltage pulse as it moves
past the wheel speed sensor. Each tooth–gap–tooth se-
ries on the wheel generates the pulses. The electronic
brake control module (EBCM) uses the frequency of these
pulses to determine wheel speed. The voltage generated
depends on the air gap between the wheel speed sensor
and the toothed wheel, and on the wheel speed.
Diagnosis
This DTC will set when the EBCM cannot identify which
wheel speed sensor is causing the malfunction. It is nec-
essary to check all wheel speed sensors and associated
wiring to determine the cause of the DTC.
Cause(s)
S Incorrect number of teeth on the toothed wheel.
S Damaged or broken teeth on the toothed wheel.
S Discontinuity or short in wheel speed sensor wiring.
Fail Action
Antilock brake system (ABS) action is disabled and the
ABS warning lamp is ON.Test Description
The number(s) below refer to step(s) on the diagnostic
table.
1. This step begins the examination of the front wheel
speed sensors.
3. This step checks for a problem with one of the front
toothed rings.
5. This step checks the front wheel speed sensors.
7. This step checks for shorts in a front wheel speed
sensor harness.
9. This step checks for opens in a front wheel speed
sensor harness.
11. This step begins a check of the rear wheel speed
sensors.
13. This step checks for a problem with one of the rear
toothed rings.
15. This step checks the rear wheel speed sensors.
17. This step checks for shorts in a rear wheel speed
sensor harness.
19. This step checks for opens in a rear wheel speed
sensor harness.

4F – 54IANTILOCK BRAKE SYSTEM
DAEWOO V–121 BL4
J3B14F04
60A Ef230A Ef5
2
42
C107 C105
2
C110
G106
A19
A13 A1 A14
C110 C202
C202WHT LT GRN
DK
GRN LT GRN/
BLK
BLK
DK BLUDK BLU
PPL/WHT
PPL/WHT ABS
TCS Parking
Brake
Hot at all times
RED REDRED/WHT
Ignition
Switch
RED
RED
I/P Cluster
EBCM8
20
22 2216 41
1211
18 1621
1
C107
10A F410AF11
32 31
43
6 62 C201
C201 C201C201
C110 C202
Hot in Run and Start
30
4
1711
C202
15
B15
DLC
(Data Link
Connector)12
G106
BLK/WHTOil Feeding
Connector
”2” Ter.
BRNBRN BRN
BRN PNK PNK PNK
19J1
59B1
ONStart Lock
Acc
IG1
19
DIAGNOSTIC TROUBLE CODE (DTC) C0550
ABS CONTROL MODULE INTERNAL FAULT
Circuit Description
The ABS control module performs various diagnostic
checks on itself. If it finds a problem, it sets DTC C0550.
Diagnosis
This procedure checks whether there is a poor ground
connection for the electronic brake control module
(EBCM).
Cause(s)
S A connector terminal is corroded.
S The EBCM is malfunctioning.
Fail Action
ABS is disabled, and the ABS warning lamp is turned ON.EBD is disabled. If the failure is intermittent, the control
module will enable the system at the next ignition cycle
and will store a history DTC C0550.
Test Description
The number(s) below refer to step(s) on the diagnostic
table.
3. This step begins the testing for a poor voltage or
ground connection.
Diagnostic Aids
It is very important to perform a thorough inspection of the
wiring and the connectors. Failure to inspect the wiring
and the connectors carefully and completely may result in
misdiagnosis, causing part replacement with the reap-
pearance of the malfunction.

4F – 56IANTILOCK BRAKE SYSTEM
DAEWOO V–121 BL4
J3B14F04
60A Ef230A Ef5
2
42
C107 C105
2
C110
G106
A19
A13 A1 A14
C110 C202
C202WHT LT GRN
DK
GRN LT GRN/
BLK
BLK
DK BLUDK BLU
PPL/WHT
PPL/WHT ABS
TCS Parking
Brake
Hot at all times
RED REDRED/WHT
Ignition
Switch
RED
RED
I/P Cluster
EBCM8
20
22 2216 41
1211
18 1621
1
C107
10A F410AF11
32 31
43
6 62 C201
C201 C201C201
C110 C202
Hot in Run and Start
30
4
1711
C202
15
B15
DLC
(Data Link
Connector)12
G106
BLK/WHTOil Feeding
Connector
”2” Ter.
BRNBRN BRN
BRN PNK PNK PNK
19J1
59B1
ONStart Lock
Acc
IG1
19
DIAGNOSTIC TROUBLE CODE (DTC) C0800
LOW VOLTAGE FAULT
Circuit Description
Proper operation of the electronic brake control module
(EBCM) requires a certain minimum voltage. The EBCM
monitors the ignition feed circuit to determine if the voltage
falls below a minimum level.
Diagnosis
This test checks for battery output, proper grounding,
blown fuses, faulty ignition switch, and problems in the cir-
cuitry.
Cause(s)
S The battery is defective.
S There is a defective ground connection.
S A connector is damaged.
S A wire is broken or shorted.
S A fuse is blown.
S The ignition switch is malfunctioning.
Fail Action
ABS action is disabled during the period of low voltage,and the ABS warning lamp is ON for the remainder of the
ignition cycle. If the failure is intermittent, the EBCM will
enable the system at the next ignition cycle and set a histo-
ry DTC C0800.
Test Description
The number(s) below refer to step(s) on the diagnostic
table.
1. This step determines whether there is voltage at
the battery and at the high current source.
7. This step checks for voltage at the ignition 1
source.
11. This step begins the check for voltage at the EBCM
end of the ABS harness.
15. This step checks for a defective ground connection.
16. This is a check for a defective EBCM connector.
Diagnostic Aids
It is very important to perform a thorough inspection of the
wiring and the connectors. Failure to do so may result in
misdiagnosis, causing part replacement with a reappear-
ance of the malfunction.

ANTILOCK BRAKE SYSTEM 4F – 59
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) C0931
OVERHEATED
DTC Description
The brake can be overheated when the TCS controls the
brake system to reduce the velocity of driving wheel. At
this moment, the EBCM calculates the brake application
time and frequency and shows the warning sign of over
heated driving wheel to the driver.Cause(s)
S EBCM show the driving wheel temperature over
400 °C.
Fail Action
TCS dose not functioning when the DTC C0931 is de-
tected.

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.

PARKING BRAKE 4G – 3
DAEWOO V–121 BL4
7. Inspect and replace any parts of doubtful strength
or quality. This can be shown by discoloration from
heat or stress.
8. Using a vernier caliper, adjust the shoe assembly to
167.6 to 167.8 mm (6.60 to 6.61 inches) by turning
the adjuster nut clockwise to increase the diameter.
Measure the shoe assembly diameter as closely as
possible to the center of the lining material.
9. Inspect and install the rotors and calipers. Refer to
Section 4E1, Rear Disc Brakes.
10. Install the parking brake cable to the backplate le-
ver on each side of the vehicle.
11. In the vehicle cabin, pull on the parking brake han-
dle. Stop after hearing two clicks.
12. Turn the rear wheel by hand until the wheel begins
to drag.
13. Release the parking brake.
14. Turn the rear wheel by hand to check the drag. Re-
adjust the cable, if necessary.
15. Repeat the process for the other rear wheel.
16. Lower the vehicle.
PARKING BRAKE LEVER
Removal Procedure
1. Release the parking brake.
2. Remove the parking brake/gearshift console hood.
Refer to Section 9G, Interior Trim.
3. Measure the thread length from the end of the pull
rod to the hex nut.
4. Remove the hex nut.
5. Remove the parking brake warning lamp switch.
Notice : The parking brake switch should be replaced if
the BRAKE warning light in the instrument panel cluster
did not glow when the parking brake was applied with the
ignition switch ON.

PARKING BRAKE 4G – 9
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
PARKING BRAKE
This braking system uses a BRAKE warning light located
in the instrument panel cluster. When the ignition switch
is in the START position, the BRAKE warning light shouldglow and go OFF when the the ignition switch returns to
the RUN position. Whenever the parking brake is applied
and the ignition switch is ON, the BRAKE warning light
should glow.
When the brake is firmly applied, the parking brake should
hold the vehicle with ample pedal travel remaining. Check
for frayed cables, rust, etc. or any condition that many in-
hibit present (or future) free movement of the parking
brake lever assembly.