DAEWOO LACETTI 2004 Service Repair Manual

HYDRAULIC BRAKES 4A – 5
DAEWOO V–121 BL4
DIAGNOSIS
BRAKE SYSTEM TESTING
Brakes should be tested on a dry, clean, reasonably
smooth and level roadway. A true test of brake perfor-
mance cannot be made if the roadway is wet, greasy, or
covered with loose dirt whereby all tires do not grip the
road equally. Testing will also be adversely affected if the
roadway is crowned so as to throw the weight so roughly
that the wheels tend to bounce.
Test the brakes at different vehicle speeds with both light
and heavy pedal pressure; however, avoid locking the
brakes and sliding the tires. Locked brakes and sliding
tires do not indicate brake efficiency since heavily braked,
but turning, wheels will stop the vehicle in less distance
than locked brakes. More tire–to–road friction is present
with a heavily–braked, turning tire than with a sliding tire.
Because of the high deceleration capability, a firmer pedal
may be felt at higher deceleration levels.
There are three major external conditions that affect brake
performance:
S Tires having unequal contact and grip of the road
will cause unequal braking. Tires must be equally
inflated, and the tread pattern of the right and the
left tires must be approximately equal.
S Unequal loading of the vehicle can affect the brake
performance since the most heavily loaded wheels
require more braking power, and thus more braking
effort, than the others.
S Misalignment of the wheels, particularly conditions
of excessive camber and caster, will cause the
brakes to pull to one side.
To check for brake fluid leaks, hold constant foot pressure
on the pedal with the engine running at idle and the shift
lever in NEUTRAL. If the pedal gradually falls away with
the constant pressure, the hydraulic system may be leak-
ing. Perform a visual check to confirm any suspected
leaks.
Check the master cylinder fluid level. While a slight drop
in the reservoir level results from normal lining wear, an ab-
normally low level indicates a leak in the system. The hy-
draulic system may be leaking either internally or external-
ly. Refer to the procedure below to check the master
cylinder. Also, the system may appear to pass this test
while still having a slight leak. If the fluid level is normal,
check the vacuum booster pushrod length. If an incorrect
pushrod length is found, adjust or replace the rod.
Check the master cylinder using the following procedure:
S Check for a cracked master cylinder casting or
brake fluid leaking around the master cylinder.
Leaks are indicated only if there is at least one drop
of fluid. A damp condition is not abnormal.S Check for a binding pedal linkage and for an incor-
rect pushrod length. If both of these parts are in
satisfactory condition, disassemble the master cyl-
inder and check for an elongated or swollen primary
cylinder or piston seals. If swollen seals are found,
substandard or contaminated brake fluid should be
suspected. If contaminated brake fluid is found, all
the components should be disassembled and
cleaned, and all the rubber components should be
replaced. All of the pipes must also be flushed.
Improper brake fluid, or mineral oil or water in the fluid,
may cause the brake fluid to boil or cause deterioration of
the rubber components. If the primary piston cups in the
master cylinder are swollen, then the rubber parts have
deteriorated. This deterioration may also be evidenced by
swollen wheel cylinder piston seals on the drum brake
wheels.
If deterioration of rubber is evident, disassemble all the hy-
draulic parts and wash the parts with alcohol. Dry these
parts with compressed air before reassembly to keep alco-
hol out of the system. Replace all the rubber parts in the
system, including the hoses. Also, when working on the
brake mechanisms, check for fluid on the linings. If exces-
sive fluid is found, replace the linings.
If the master cylinder piston seals are in satisfactory condi-
tion, check for leaks or excessive heat conditions. If these
conditions are not found, drain the fluid, flush the master
cylinder with brake fluid, refill the master cylinder, and
bleed the system. Refer to ”Manual Bleeding the Brakes”
or”Pressure Bleeding the Brakes” in this section.
BRAKE HOSE INSPECTION
The hydraulic brake hoses should be inspected at least
twice a year. The brake hose assembly should be checked
for road hazard damage, cracks, chafing of the outer cov-
er, and for leaks or blisters. Inspect the hoses for proper
routing and mounting. A brake hose that rubs on a suspen-
sion component will wear and eventually fail. A light and
a mirror may be needed for an adequate inspection. If any
of the above conditions are observed on the brake hose,
adjust or replace the hose as necessary.
WARNING LAMP OPERATION
This brake system uses a BRAKE warning lamp located
in the instrument panel cluster. When the ignition switch
is in the START position, the BRAKE warning lamp should
glow and go OFF when the ignition switch returns to the
RUN position.
The following conditions will activate the BRAKE lamp:
S Parking brake applied. The light should be ON
whenever the parking brake is applied and the igni-
tion switch is ON.
S Low fluid level. A low fluid level in the master cylin-
der will turn the BRAKE lamp ON.
S EBD system is disabled. The light should be ON
when the EBD system is malfunctioning.

4A – 6IHYDRAULIC BRAKES
DAEWOO V–121 BL4
STOP LAMP WARNING CIRCUIT DIAGNOSIS
J3B14A03
10A30
F4
32
A19
A13 A14 A1 A2B15 C201
31C201IP/Fuse
Block C201
C202
C110C108 S301 WHT
BRN
BRN
Parking
Brake
SwitchBrake
Fluid
Switch
BLKBRN LT GRN
DK
GRN
DK
GRN LT GRN/
BLK
LT GRN/
BLKPPL/
WHT
PPL/
WHT
PPL/
WHTPPL/
WHT PPL/
WHT
PPL/
WHT ABS
Warning
Lamp TCS
Active
Warning
Lamp Parking
Brake
Warning
Lamp Charging
Warning
Hot in Run and Start
PNK
Cluster PNK
EBCM”L” Ter.
Generator 1 12
2
20 2222 16 41 13
3
4
11 1 215
8
21
G303
Test Description
The number(s) below refer to step(s) on the diagnostic
table.
1. When the ignition is turned ON, the brake warning
lamp should initially illuminate and then dim for ABS
equipped vehicles. This is done as a bulb check.
On vehicles that are not equipped with ABS, the
brake warning lamp should only illuminate when
either the brake fluid reservoir is low or the parking
brake is applied.
7. The brake fluid level switch is a normally open
switch. If the brake warning lamp is off after discon-
necting the switch, the brake fluid level switch is
stuck closed.9. If the brake warning lamp is still on after discon-
necting the parking brake switch, there is a short to
ground in the wire to the parking brake switch.
12. If the other checks have been properly performed
and the brake warning lamp is off after disconnect-
ing the electronic brake control module (EBCM) J1
connector, the EBCM is faulty.
19. If the brake warning lamp does not operate while
performing any of the functions, the fault should be
in the ignition feed to the circuit.
24. This step determines if the problem is in the ignition
feed to the circuit or in the instrument cluster.
30. The brake warning lamp should illuminate when
jumpering the parking brake connector to ground.
32. If the brake warning lamp is on after jumpering the
brake fluid level switch terminals, the switch is
faulty.

HYDRAULIC BRAKES 4A – 7
DAEWOO V–121 BL4
Stop Lamp Warning Circuit Diagnosis
StepActionValue(s)YesNo
1Turn the ignition ON.
Is the brake warning lamp always on?–Go to Step 2Go to Step 18
2Check the ABS warning lamp.
Is the ABS warning lamp also on?–Go to Step 3Go to Step 4
3Use a scan tool to check for diagnostic trouble codes
(DTCs) and follow the procedures for any DTCs
found.
Is the lamp still on?–Go to Step 4System OK
4Release the parking brake fully.
Is the lamp off?–System OKGo to Step 5
5Check the brake fluid level.
Is the fluid level OK?–Go to Step 7Go to Step 6
61. Fill the brake fluid reservoir with clean DOT 3
equivalent hydraulic fluid.
2. Replace the cap on the fluid reservoir.
Is the lamp on?– Go to Step 7System OK
7Disconnect the harness connector from the brake
fluid level switch.
Is the lamp on?–Go to Step 9Go to Step 8
8Replace the brake fluid level switch.
Is the repair complete?–System OK–
91. Connect the brake fluid level switch.
2. Disconnect the parking brake switch.
Is the lamp on?–Go to Step 11Go to Step 10
10Replace the parking brake switch.
Is the repair complete?–System OK–
11Connect the parking brake switch.
Is the vehicle equipped with ABS?–Go to Step 12Go to Step 14
121. Turn the ignition OFF.
2. Disconnect the electronic brake control module
(EBCM) connector.
3. Turn the ignition ON.
Is the lamp on?–Go to Step 14Go to Step 13
13Replace the electronic brake control module
(EBCM).
Is the repair complete?–System OK–
141. Turn the ignition OFF.
2. Connect the EBCM connector.
3. Check for a short to ground in the wiring be-
tween the instrument cluster terminal A19(B15)
and the brake fluid level switch.
Is the problem found?–Go to Step 17Go to Step 15
15Check for a short to ground in the wiring between the
instrument cluster terminal A19(B15) and the park-
ing brake switch.
Is the problem found?–Go to Step 17Go to Step 16

4A – 8IHYDRAULIC BRAKES
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
16Check for a short to ground in the wiring between the
instrument cluster terminal A19(B15) and the EBCM
connector terminal 21.
Is the problem found?–Go to Step 17Go to Step 18
17Repair the wiring as needed.
Is the repair complete?–System OK–
18Check the brake lamp after doing each of the follow-
ing functions:
S Apply the parking brake.
S Remove the cap from the brake fluid reservoir.
S On vehicles equipped with ABS, command the
lamp on using a scan tool.
Does the brake warning lamp operate for all of these
conditions?–System OKGo to Step 19
19When the operations listed in step 18 were per-
formed, the brake warning lamp did not function.
Did the brake warning lamp fail to light for all of the
operations listed in step 18?–Go to Step 20Go to Step 27
201. Turn the ignition OFF.
2. Inspect the kick panel fuse F4.
Is the fuse OK?–Go to Step 22Go to Step 21
21Replace the fuse.
Is the repair complete?–System OK–
22Inspect the brake warning lamp bulb.
Is the bulb OK?–Go to Step 24Go to Step 23
23Replace the bulb.
Is the repair complete?–System OK–
241. Disconnect the instrument cluster connector.
2. Turn the ignition ON.
3. Measure the voltage at the instrument cluster
connector terminal A19(B15).
Does the voltage measure within the value speci-
fied?11–14 vGo to Step 25Go to Step 26
251. Turn the ignition OFF.
2. Repair the open in the instrument cluster.
Is the repair complete?–System OK–
261. Turn the ignition OFF.
2. Repair the open in the wiring between the in-
strument cluster connector terminal A19(B15)
and the ignition switch.
Is the repair complete?–System OK–
27Apply the parking brake again.
Does the parking brake warning lamp operate with
the parking brake applied?–Go to Step 28Go to Step 30
28Remove the brake fluid reservoir cap.
Does the parking brake warning lamp operate with
the cap from the brake fluid reservoir removed?–Go to Step 29Go to Step 32
29Check for an open between the instrument cluster
connector terminal A1 and the EBCM connector ter-
minal 21.
Is the problem found?–Go to Step 17Go to Step 13

HYDRAULIC BRAKES 4A – 9
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
301. Turn the ignition ON.
2. Disconnect the parking brake switch.
3. Jumper the parking brake switch connector
terminal to ground.
Is the lamp on?–Go to Step 10Go to Step 31
311. Turn the ignition OFF.
2. Repair the open in the wire between the instru-
ment cluster connector terminal A1 and the
parking brake switch connector terminal.
3. Is the repair complete?
Is the repair complete?–System OK–
321. Disconnect the brake fluid level switch.
2. Turn the ignition ON.
3. Jumper the brake fluid level switch connector
terminals.
Is the lamp on?–Go to Step 8Go to Step 33
331. Turn the ignition OFF.
2. Connect a test light between battery positive
and the BRN/WHT wire terminal of the brake
fluid level switch.
Is the test light on?–Go to Step 34Go to Step 35
34Repair the open in the wiring between ground and
the brake fluid level switch.
Is the repair complete?–System OK–
35Repair the open in the wiring between the instrument
cluster connector terminal A1 and the brake fluid lev-
el switch.
Is the repair complete?–System OK–

4A – 10IHYDRAULIC BRAKES
DAEWOO V–121 BL4
MAINTENANCE AND REPAIR
ON–VEHICLE SERVICE
MANUAL BLEEDING THE BRAKES
(Left–Hand Drive Shown, Right–Hand Drive
Similar)
1. Remove the booster reserve by applying the brakes
several times with the engine OFF until all the re-
serve is depleted.
Important : If the master cylinder is known or suspected
to have air in the bore, then it must be bled before any
wheel cylinder or caliper is bled.
2. Fill the master cylinder reservoir with brake fluid.
Keep the master cylinder at least one–half full of
fluid during the bleeding operation.
3. Disconnect the front brake line(s) at the master cyl-
inder.
4. Allow the brake fluid to fill the master cylinder until it
begins to flow from the front pipe connector port.
5. Connect the front brake line(s) to the master cylin-
der.
Tighten
Tighten the brake lines to 16 NSm (12 lb–ft).

HYDRAULIC BRAKES 4A – 11
DAEWOO V–121 BL4
6. Slowly push and hold the brake pedal one time.
7. Loosen the front brake line at the master cylinder to
purge air from the cylinder.
8. Tighten the brake line (as in step 5), and then re-
lease the brake pedal slowly. Wait 15 seconds be-
fore proceeding to the next step.
9. Repeat the sequence, including the 15–second
wait, until all the air is removed from the master
cylinder bore.
Notice : Care must be taken to prevent brake fluid from
contacting any painted surface to prevent damage to the
paint finish.
10. After all the air has been removed at the forward
connection(s), bleed the master cylinder at the rear
(cowl) connection(s) in the same manner as with
the front connections.
Important : For vehicles equipped with a non–antilock
braking system, the bleeding sequence is as follows: right
rear, left rear, left front and right front. For ABS vehicles,
refer to Section 4F, Antilock Brake System for the correct
sequence and bleeding procedure.
11. Attach a transparent tube over the valve. Allow the
tube to hang submerged in brake fluid in a transpar-
ent container.

4A – 12IHYDRAULIC BRAKES
DAEWOO V–121 BL4
12. Slowly push and hold the brake pedal one time.
13. Remove the bleeder valve dust cover and loosen
the bleeder screw to purge the air from the cylinder.
14. Tighten the bleeder screw.
Tighten
Tighten the bleeder screw to 8 NSm (71 lb–in).
15. Slowly release the brake pedal. Wait 15 seconds
before proceeding with the next step.
Important : Rapid pumping of the brake pedal pushes the
master cylinder secondary piston down the bore in a man-
ner that makes it difficult to bleed the system.
16. Repeat the sequence, including the 15–second
wait, until all the air is removed. It may be neces-
sary to repeat the sequence 10 or more times to
remove all the air.
17. Locate the front bleeder caps.
18. Proceed to bleed the front brakes following the ap-
propriate sequence, beginning with step 12.
19. Check the brake pedal for sponginess. Repeat the
entire bleeding procedure to correct this condition.
20. Replace the bleeder valve dust cover.
PRESSURE BLEEDING THE BRAKES
Notice : Pressure bleeding equipment must be of the dia-
phragm type. It must have a rubber diaphragm between
the air supply and the brake fluid to prevent air, moisture,
oil, and other contaminants from entering the hydraulic
system. Contamination could lead to deterioration of the
braking components and loss of braking action.
1. Disconnect the master cylinder electrical connector.
2. Remove the master cylinder reservoir cap.
3. Connect the bleeder with the adapter to the master
cylinder reservoir.
4. For vehicles with the antilock braking system
(ABS), locate and remove the hydraulic modulator
bleeder valves. Refer to Section 4F, Antilock Brake
System.
5. Charge the bleeder ball to 140 to 172 kPa (20 to 25
psi).
6. Connect the line to the adapter. Open the line
valve.
7. Raise and suitably support the vehicle.
Important : The bleeding sequence is as follows: right
rear, left front, left rear and right front.

HYDRAULIC BRAKES 4A – 13
DAEWOO V–121 BL4
8. Attach the bleeder hose to the bleeder valve. Sub-
merge the opposite end of the hose in a clean con-
tainer partially filled with brake fluid.
9. Open the bleeder valve one–half to three–fourths
turn and allow the fluid to flow until no air is seen in
the fluid.
Notice : After the bleeding operation, the brake reservoir
may be pressurized. While disconnecting the bleeder
hose or the unthreaded adapter cap, cover the cap and the
connection with a shop towel to protect painted surfaces
from contact with the brake fluid.
10. Inspect the brake pedal for sponginess. Repeat the
entire bleeding procedure to correct this condition.
BRAKE HOSE REAR
Removal Procedure
1. Raise and suitably support the vehicle.
2. Remove the brake hose retainer.
3. Disconnect the brake pipe line from the disc brake
hose.
4. Remove the rear disc brake hose retainer and the
brake hose from the bracket on the steering
knuckle shaft.

4A – 14IHYDRAULIC BRAKES
DAEWOO V–121 BL4
5. Remove the rear disc brake hose from the caliper.
Installation Procedure
1. Connect the brake pipe line to the brake hose.
Tighten
Tighten the brake line to 16 NSm (12 lb–ft).
2. Install the retainer onto the rear brake hose bracket
from the wheel house.
3. Install the rear disc brake hose to the caliper.
Tighten
Tighten the rear disc brake hose–to–caliper bolt to 32
NSm (24 lb–ft).
4. Install the rear disc brake hose and retainer on the
bracket on the steering knuckle shaft.
5. Lower the vehicle.
6. Bleed the brake system. Refer to ”Manual Bleeding
the Brakes” in this section.
7. Check the brake system for leaks.
BRAKE HOSE FRONT
Removal Procedure
1. Raise and suitably support the vehicle.
2. Remove the retainer.
3. Disconnect the brake pipe line from the brake hose
support bracket on the wheel housing on each side
of the vehicle.
4. Disconnect the brake hose from the ”C” bracket on
the steering knuckle shaft.
5. Remove the bolt from the brake caliper.
6. Remove the seal rings and the disc brake hose.