4A – 2IHYDRAULIC BRAKES
DAEWOO V–121 BL4
SPECIFICATIONS
GENERAL SPECIFCATIONS
1.4/1.6/1.8/2.0 DOHC Engine
ApplicationMillimetersInches
Brake Drums:
Inside Diameter
Maximum Rebore Diameter
Out–of–Round200.00
201.00
0.047.87
7.91
0.0016
Front Brake Rotors:
Discard Thickness
Lateral Runout (Installed)
Rotor Diameter
Rotor Thickness (New)
Thickness Variation22.00
0.030
256
24.00
0.010.87
0.001
10.07
0.95
0.0004
Rear Brake Rotors:
Discard Thickness
Lateral Runout (Installed)
Rotor Diameter
Rotor Thickness (New)
Thickness Variation8
0.030
258
10.4
0.010.31
0.001
10.15
0.40
0.0004
Master Cylinder:
Bore Diameter (Nominal)
Bore Diameter (Maximum)22.22
22.290.875
0.878
Caliper:
Minimum Piston Diameter (Front)
Minimum Piston Diameter (Rear)54.00
322.126
1.260
Wheel Cylinder Diameter:
Maximum
Nominal20.7
20.640.815
0.812
FASTENER TIGHTENING SPECIFICATIONS
ApplicationNSmLb–FtLb–In
Bleeder Screw8–71
Brake Lines1612–
Brake Pedal–to–Pedal Bracket Hex Nut1813–
Front Disc Brake Hose–to–Caliper Bolt4030–
Rear Disc Brake Hose–to–Caliper Bol3224–
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 – 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).
SECTION : 4C
POWER BOOSTER
TABLE OF CONTENTS
SPECIFICATIONS4C–1 . . . . . . . . . . . . . . . . . . . . . . . . . .
Fasrener Tightening Specifications 4C–1. . . . . . . . . .
DIAGNOSIS4C–1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Booster Functional Check 4C–1. . . . . . . . . . . .
MAINTENANCE AND REPAIR4C–2 . . . . . . . . . . . . . . . ON–VEHICLE SERVICE 4C–2. . . . . . . . . . . . . . . . . . . . .
Vacuum Hose 4C–2. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Booster Assembly 4C–2. . . . . . . . . . . . . . . . . . .
GENERAL DESCRIPTION AND SYSTEM
OPERATION4C–6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Booster 4C–6. . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPECIFICATIONS
FASRENER TIGHTENING SPECIFICATIONS
ApplicationNSmLb–FtLb–In
Booster–to–Bracket Nuts (Right–Hand Drive)2216–
Booster–to–Dash Panel Nut (Left–Hand
Drive)2216–
Booster Hex Nut and Pushrod Clevis1813–
Brake Line Fittings1612–
DIAGNOSIS
POWER BOOSTER FUNCTIONAL
CHECK
1. With the engine stopped, eliminate vacuum in the
booster by pumping the brake pedal several times.
2. Push the pedal down and hold in this position.
3. Start the engine.4. The booster is OK if the pedal drops further be-
cause of extra force produced.
If the brake pedal does not drop, the vacuum system (vac-
uum hoses, check valve, etc.) is probably defective and
should be checked.
If no defect is revealed by checking the vacuum system,
the defect is in the booster itself.
ANTILOCK BRAKE SYSTEM 4F – 11
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
17Replace the ABS unit.
Is the repair complete?–System OK–
18Repair the continuity problem between terminal 19
of the EBCM connector and ground G106.
Is the repair complete?–System OK–
191. Turn the ignition switch to LOCK.
2. Check fuse F4 in the I/P fuse block.
Is this fuse blown?–Go to Step 20Go to Step 21
20Replace fuse F4.
Is the repair complete?–System OK–
21Check fuse EF5 in the engine fuse block.
Is this fuse blown?–Go to Step 22Go to Step 23
22Replace fuse EF5.
Is the repair complete?–System OK–
23Measure the voltage at terminal 2 of the ignition
switch connector by backprobing.
Does the voltage match the specified value?11–14 vGo to Step 25Go to Step 24
241. Check circuit RED between terminal 4 of C105
at the engine fuse block and terminal 2 of the
ignition switch for continuity.
2. Repair any open or high resistance found.
Is the repair complete?–System OK–
251. Turn the ignition switch to ON.
2. Backprobe terminal 4 (PNK) of the ignition
switch connector.
Does the voltage match the specified value?11–14 vGo to Step 27Go to Step 26
26Replace the ignition switch.
Is the repair complete?–System OK–
271. Turn the ignition switch to LOCK.
2. Check circuit PNK from terminal 4 of the igni-
tion switch to fuse F4 in the I/P fuse block.
Does the ohmmeter show the specified value?Go to Step 28Go to Step 29
28Repair the open or the high resistance.
Is the repair complete?–System OK–
291. Remove the instrument cluster.
2. Check circuit PNK from fuse F4 to terminal
A19 of the I/P cluster connector B.
3. Repair any open or high resistance found in a
wiring harness, splice pack, or connector.
Is the repair complete?–System OK–
ANTILOCK BRAKE SYSTEM 4F – 13
DAEWOO V–121 BL4
Power Supply to Control Module, No DTCs Stored
StepActionValue(s)YesNo
1Check the voltage at the battery.
Is the voltage within the specified value?11–14 vGo to Step 3Go to Step 2
2Charge or replace the battery as required.
Is the repair complete?–System OK–
3Check fuse EF2 in the engine fuse block.
Is the fuse blown?–Go to Step 4Go to Step 8
41. Replace fuse EF2.
2. Turn the ignition to ON.
Does the fuse blow again?–Go to Step 6Go to Step 5
5Check the ABS function.
Is the repair complete?–System OK–
61. Turn the ignition to OFF.
2. Remove fuse EF2.
3. Disconnect the ABS connector from the
EBCM.
4. Measure the resistance to ground at terminals
17 and 18.
Does the ohmmeter show the specified value?0 WGo to Step 7Go to Step 25
7Repair the short to ground in circuit RED between
terminal 1 of engine fuse block connector C107 and
the ABS harness EBCM connector.
Is the repair complete?–System OK–
8Check fuse EF5 in the engine fuse block.
Is the fuse blown?–Go to Step 9Go to Step 13
91. Replace fuse EF5.
2. Turn the ignition to ON.
Does the fuse blow again?–Go to Step 11Go to Step 10
10Check the ABS function.
Is the repair complete?–System OK–
111. Turn the ignition to OFF.
2. Remove fuse EF5.
3. Disconnect ABS connector from the EBCM.
4. Measure the resistance to ground at terminal
15.
Does the ohmmeter show the specified value?0 WGo to Step 12Go to Step 25
121. Examine circuit RED between terminal 4 of en-
gine fuse block connector C105 and terminal 2
of the ignition switch.
2. Examine circuit PNK from terminal 4 of the
ignition switch to fuse F11 in the I/P fuse block.
3. Examine circuit PNK from fuse F11 in the I/P
fuse block to terminal 15 of the ABS EBCM
connector.
4. Repair any short to ground found in the wiring
or the ignition switch.
Is the repair complete?–System OK–
13Check fuse F11 in the I/P fuse block.
Is the fuse blown?–Go to Step 14Go to Step 18
4F – 14IANTILOCK BRAKE SYSTEM
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
141. Replace fuse F11.
2. Turn the ignition to ON.
Does the fuse blow again?–Go to Step 16Go to Step 15
15Check the ABS function.
Is the repair complete?–System OK–
161. Turn the ignition to OFF.
2. Remove fuse F11.
3. Disconnect ABS connector from the EBCM.
4. Measure the resistance to ground at terminal
15.
Does the ohmmeter show the specified value?0 WGo to Step 17Go to Step 25
17Repair the short to ground in circuit PNK fuse F11 of
the I/P fuse block and terminal 15 of the ABS har-
ness EBCM connector.
Is the repair complete?–System OK–
181. Disconnect the EBCM connector from the
EBCM.
2. Turn the ignition to ON.
3. Check for the presence of battery voltage be-
tween ground and terminal 17, and between
ground and terminal 18.
Is the voltage within the specified value?11–14 vGo to Step 20Go to Step 19
191. Turn the ignition switch to OFF.
2. Trace the RED wires between terminals 17 and
18 of the EBCM connector to terminal 1 of con-
nector C107 at the engine fuse block.
3. Repair the open in this circuit.
Is the repair complete?–System OK–
20Check the voltage between ground and terminal 15
of the EBCM connector.
Is the voltage within the specified value?11–14 vGo to Step 22Go to Step 21
211. Turn the ignition switch to OFF.
2. Trace circuit PNK between terminal 15 of the
ABS harness EBCM connector to fuse F11 in
the I/P fuse block.
3. Trace circuit PNK from fuse F11 of the I/P fuse
block to terminal 4 (IG1) of the ignition switch.
4. Trace circuit RED from terminal 2 (B1) of the
ignition switch to terminal 4 of connector C105
at the engine fuse block and to fuse EF5.
5. Repair the open in the wiring or possibly bad
connector terminal, defective ignition switch, or
blown fuse EF5.
Is the repair complete?–System OK–
221. Turn the ignition to OFF.
2. Check the resistance between ground and ter-
minals 19 and 16 of the EBCM connector.
Does the ohmmeter show the specified value?0 WGo to Step 23Go to Step 26
23Examine terminals 15, 19, 17, 18, and 16 of the
EBCM connector.
Is there a defective terminal?–Go to Step 24Go to Step 25
4F – 20IANTILOCK BRAKE SYSTEM
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
13Repair the contact at the I/P cluster connector termi-
nal A1.
Is the repair complete?–System OK–
14Check the wiring harnesses and connectors in cir-
cuit PPL/WHT from the I/P cluster terminal A1 to ter-
minal 21 of the EBCM connector.
Does the ohmmeter show the specified value?Go to Step 15Go to Step 16
15Repair the open or high resistance found.
Is the repair complete?–System OK–
16Check for continuity between terminal 19 of the ABS
connector and ground G106.
Does the ground connection match the specified val-
ue?0 WGo to Step 17Go to Step 18
17Replace the ABS unit.
Is the repair complete?–System OK–
18Repair the continuity problem between terminal 19
of the EBCM connector and ground G106.
Is the repair complete?–System OK–
191. Turn the ignition switch to LOCK.
2. Check fuse F4 in the I/P fuse block.
Is this fuse blown?–Go to Step 20Go to Step 21
20Replace fuse F4.
Is the repair complete?–System OK–
21Check fuse EF5 in the engine fuse block.
Is this fuse blown?–Go to Step 22Go to Step 23
22Replace fuse EF5.
Is the repair complete?–System OK–
23Measure the voltage at terminal 2 of the ignition
switch connector by backprobing.
Is the voltage within the specified value?11–14 vGo to Step 25Go to Step 24
241. Check circuit RED between terminal 4 of C105
at the engine fuse block and terminal 2 of the
ignition switch for continuity.
2. Repair any open or high resistance found.
Is the repair complete?–System OK–
251. Turn the ignition switch to ON.
2. Backprobe terminal 4 (PNK) of the ignition
switch connector.
Is the voltage within the specified value?11–14 vGo to Step 27Go to Step 26
26Replace the ignition switch.
Is the repair complete?–System OK–
271. Turn the ignition switch to LOCK.
2. Check circuit PNK from terminal 4 of the igni-
tion switch to fuse F4 in the I/P fuse block.
Does the ohmmeter show the specified value?Go to Step 28Go to Step 29