1F – 62IENGINE CONTROLS
DAEWOO V–121 BL4
FUEL SYSTEM DIAGNOSIS
Circuit Description
The fuel pump is an in–tank type mounted to a fuel sender
assembly. The fuel pump will remain on as long as the en-
gine is cranking or running and the Engine Control Module
(ECM) is receiving reference pulses from the crankshaft
position (CKP) sensor. If there are no reference pulses,
the ECM will turn off the fuel pump two seconds after the
ignition switch is turned ON or two seconds after the en-
gine stops running. The fuel pump delivers fuel to the fuel
rail and the fuel injectors, where the fuel system pressure
is controlled from 284 to 325 kPa (41 to 47 psi) by the fuel
pressure regulator. The excess fuel is returned to the fuel
tank.
Test Description
The number(s) below refer to step(s) on the diagnostic
table.
2. When the engine is idling, the intake manifold vacu-
um is high. This vacuum is applied to the fuel pres-
sure regulator diaphragm, offsetting the spring
pressure inside the fuel pressure regulator and low-
ering the fuel pressure.10. If there is fuel bleeding back through the fuel return
outlet, this is due to a faulty fuel pressure regulator.
14. Another symptom often present when the fuel injec-
tors are leaking is hard starting. Leaking fuel injec-
tors can cause a flooding condition.
23. Fuel leaking from the fuel pump inlet is due to a
faulty one–way check valve in the fuel pump.
CAUTION : The fuel system is under pressure. To
avoid fuel spillage and the risk of personal injury or
fire, it is necessary to relieve the fuel system pressure
before disconnecting the fuel lines.
CAUTION : Do not pinch or restrict nylon fuel lines to
avoid damage that could cause a fuel leak, resulting
in possible fire or personal injury.
Fuel Pressure Relief Procedure
1. Remove the fuel cap.
2. Remove the fuel pump fuse EF18 from the engine
fuse box.
3. Start the engine and allow the engine to stall.
4. Crank the engine for an additional 10 seconds.
Fuel System Diagnosis
StepActionValue(s)YesNo
11. Relieve the fuel system pressure.
2. Install a fuel pressure gauge.
3. Turn the ignition ON.
Is the fuel pressure within the values specified and
holding steady?284~325 kPa
(41~47psi)Go to Step 2Go to Step 4
21. Allow the engine to idle.
2. Disconnect the vacuum hose from the fuel
pressure regulator.
3. Connect a vacuum pump with a gauge to the
fuel pressure regulator vacuum port.
4. Apply 41~47 kPa (12~14 in. Hg) of vacuum to
the fuel pressure regulator.
Does the fuel pressure decrease?–Go to Step 3Go to Step 15
31. Locate and correct the cause of the vacuum
restriction to the fuel pressure regulator.
2. Confirm the operation of the fuel pressure reg-
ulator.
Is the repair complete?–System OK–
41. Relieve the fuel system pressure.
2. Install a fuel pressure gauge.
3. Turn the ignition ON.
Is the fuel pressure within the values specified but
not holding steady?284~325 kPa
(41~47psi)Go to Step 5Go to Step 16
5Inspect the fuel lines for a leak.
Is the problem found?–Go to Step 6Go to Step 7
SECTION : 4A
HYDRAULIC BRAKES
CAUTION : Disconnect the negative battery cable before removing or installing any electrical unit or when a tool
or equipment could easily come in contact with exposed electrical terminals. Disconnecting this cable will help
prevent personal injury and damage to the vehicle. The ignition must also be in LOCK unless otherwise noted.
TABLE OF CONTENTS
SPECIFICATIONS4A–2 . . . . . . . . . . . . . . . . . . . . . . . . . .
General Specifcations 4A–2. . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specifications 4A–2. . . . . . . . . .
COMPONENT LOCATOR4A–3 . . . . . . . . . . . . . . . . . . . .
Brake System (ABS) 4A–3. . . . . . . . . . . . . . . . . . . . . . .
Brake System (NON–ABS) 4A–4. . . . . . . . . . . . . . . . .
DIAGNOSIS4A–5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake System Testing 4A–5. . . . . . . . . . . . . . . . . . . . .
Brake Hose Inspection 4A–5. . . . . . . . . . . . . . . . . . . . .
Warning Lamp Operation 4A–5. . . . . . . . . . . . . . . . . . .
Stop Lamp Warning Circuit Diagnosis 4A–6. . . . . . . . MAINTENANCE AND REPAIR4A–10 . . . . . . . . . . . . . .
ON–VEHICLE SERVICE 4A–10. . . . . . . . . . . . . . . . . . . .
Manual Bleeding the Brakes 4A–10. . . . . . . . . . . . . . .
Pressure Bleeding the Brakes 4A–12. . . . . . . . . . . . . .
Brake Hose Rear 4A–13. . . . . . . . . . . . . . . . . . . . . . . . .
Brake Hose Front 4A–14. . . . . . . . . . . . . . . . . . . . . . . . .
Stoplamp Switch 4A–15. . . . . . . . . . . . . . . . . . . . . . . . .
Brake Pedal 4A–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GENERAL DESCRIPTION AND SYSTEM
OPERATION4A–17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Warning Lamp Operation 4A–17. . . . . . . . . . . . . . . . . .
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).
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.
SECTION : 4F
ANTILOCK BRAKE SYSTEM
CAUTION : Disconnect the negative battery cable before removing or installing any electrical unit or when a tool
or equipment could easily come in contact with exposed electrical terminals. Disconnecting this cable will help
prevent personal injury and damage to the vehicle. The ignition must also be in LOCK unless otherwise noted.
TABLE OF CONTENTS
SPECIFICATIONS4F–2 . . . . . . . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specifications 4F–2. . . . . . . . . .
SPECIAL TOOLS4F–2 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Tools Table 4F–2. . . . . . . . . . . . . . . . . . . . . . . .
SCHEMATIC AND ROUTING DIAGRAMS4F–3 . . . . .
Abs System Circuit (I) 4F–3. . . . . . . . . . . . . . . . . . . . . .
Abs System Circuit (II) 4F–4. . . . . . . . . . . . . . . . . . . . .
Ebcm Connector Face View 4F–5. . . . . . . . . . . . . . . . .
COMPONENT LOCATOR4F–6 . . . . . . . . . . . . . . . . . . . .
ABS/EBD System Drive 4F–6. . . . . . . . . . . . . . . . . . . .
DIAGNOSIS4F–7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Circuit Check 4F–7. . . . . . . . . . . . . . . . . . .
ABS Indicator Lamp Inoperative 4F–9. . . . . . . . . . . . .
Power Supply to Control Module,
No DTCs Stored 4F–12. . . . . . . . . . . . . . . . . . . . . . . .
ABS Indicator Lamp Illuminated Continuously,
No DTCs Stored 4F–16. . . . . . . . . . . . . . . . . . . . . . . .
Electronic Brake–Force Distribution (EBD)
System Indicator Lamp Inoperative 4F–18. . . . . . . .
SELF–DIAGNOSTICS 4F–22. . . . . . . . . . . . . . . . . . . .
DISPLAYING DTCs 4F–22. . . . . . . . . . . . . . . . . . . . . . .
CLEARING DTCs 4F–22. . . . . . . . . . . . . . . . . . . . . . . .
INTERMITTENTS AND POOR
CONNECTIONS 4F–22. . . . . . . . . . . . . . . . . . . . . . . .
DTC C0035 Left Front Wheel Speed Sensor
Circuit Malfunction 4F–23. . . . . . . . . . . . . . . . . . . . . .
DTC C0040 Right Front Wheel Speed Sensor
Circuit Malfunction 4F–26. . . . . . . . . . . . . . . . . . . . . .
DTC C0045 Left Rear Wheel Speed Sensor
Circuit Malfunction 4F–29. . . . . . . . . . . . . . . . . . . . . .
DTC C0050 Right Rear Wheel Speed Sensor
Circuit Malfunction 4F–32. . . . . . . . . . . . . . . . . . . . . .
DTC C0060/C0065 Left Front Inlet and
Outlet Valve Solenoid Fault 4F–35. . . . . . . . . . . . . . .
DTC C0070/C0075 Right Front Inlet and
Outlet Valve Solenoid Fault 4F–37. . . . . . . . . . . . . . . DTC C0080/C0085 Left Rear Inlet and
Outlet Valve Solenoid Fault 4F–39. . . . . . . . . . . . . . .
DTC C0090/C0095 Right Rear Inlet and
Outlet Valve Solenoid Fault 4F–41. . . . . . . . . . . . . . .
DTC C0110 Pump Motor Circuit Malfunction 4F–43. .
DTC C0121 Valve Relay Circuit Malfunction 4F–45. .
DTC C0161 ABS Brake Switch Circuit
Malfunction 4F–47. . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC C0245 Wheel Speed Sensor Frequency
Error 4F–50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC C0550 ABS Control Module Internal
Fault 4F–54. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC C0800 Low Voltage Fault 4F–56. . . . . . . . . . . . .
DTC C0931 Overheated 4F–59. . . . . . . . . . . . . . . . . . .
MAINTENANCE AND REPAIR4F–60 . . . . . . . . . . . . . .
ON–VEHICLE SERVICE 4F–60. . . . . . . . . . . . . . . . . . . .
Service Precautions 4F–60. . . . . . . . . . . . . . . . . . . . . . .
Bleeding System 4F–61. . . . . . . . . . . . . . . . . . . . . . . . .
ABS 5.3 Assembly 4F–61. . . . . . . . . . . . . . . . . . . . . . . .
Front Wheel Speed Sensor 4F–62. . . . . . . . . . . . . . . .
Front Wheel Speed Sensor Jumper Harness 4F–63.
Rear Wheel Speed Sensor 4F–64. . . . . . . . . . . . . . . . .
GENERAL DESCRIPTION AND SYSTEM
OPERATION4F–65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Basic Knowledge Required 4F–65. . . . . . . . . . . . . . . . .
ABS System Components 4F–65. . . . . . . . . . . . . . . . .
Base Braking Mode 4F–65. . . . . . . . . . . . . . . . . . . . . . .
Antilock Braking Mode 4F–66. . . . . . . . . . . . . . . . . . . . .
EBD System 4F–69. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electronic Brake–Force Distribution (EBD) Failure
Matrix 4F–70. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tires and ABS/EBD 4F–71. . . . . . . . . . . . . . . . . . . . . . .
Electronic Brake Control Module (EBCM) 4F–71. . . .
Front Wheel Speed Sensors 4F–71. . . . . . . . . . . . . . .
Front Wheel Speed Sensor Rings 4F–71. . . . . . . . . . .
Rear Wheel Speed Sensors and Rings 4F–71. . . . . .
Valve Relay and Pump Motor Relay 4F–71. . . . . . . . .