2003 DAEWOO MATIZ low oil pressure

DAEWOO M-150 BL2
SECTION 1F
ENGINE CONTROLS
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
Description and Operation 1F-4. . . . . . . . . . . . . . . . . .
Ignition System Operation 1F-4. . . . . . . . . . . . . . . . . .
Electronic Ignition System Ignition Coil 1F-4. . . . . . .
Crankshaft Position Sensor 1F-4. . . . . . . . . . . . . . . . .
Camshaft Position Sensor 1F-4. . . . . . . . . . . . . . . . . .
Idle Air System Operation 1F-4. . . . . . . . . . . . . . . . . .
Fuel Control System Operation 1F-4. . . . . . . . . . . . . .
Evaporative Emission Control System
Operation 1F-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Controlled Charcoal Canister 1F-5. . . . . . . . . . . . . . . .
Positive Crankcase Ventilation Control System
Operation 1F-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature Sensor 1F-6. . . . . . . . .
Throttle Position Sensor 1F-6. . . . . . . . . . . . . . . . . . . .
Catalyst Monitor Oxygen Sensors 1F-6. . . . . . . . . . .
Electric Exhaust Gas Recirculation Valve 1F-6. . . . .
Intake Air Temperature Sensor 1F-7. . . . . . . . . . . . . .
Idle Air Control Valve 1F-7. . . . . . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure Sensor 1F-7. . . . . . . . . .
Engine Control Module 1F-8. . . . . . . . . . . . . . . . . . . . .
Fuel Injector 1F-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Cutoff Switch (Inertia Switch) 1F-8. . . . . . . . . . .
Knock Sensor 1F-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Variable Reluctance (VR) Sensor 1F-8. . . . . . . . . . . .
Octane Number Connector 1F-8. . . . . . . . . . . . . . . . .
Strategy-Based Diagnostics 1F-9. . . . . . . . . . . . . . . .
EOBD Serviceability Issues 1F-9. . . . . . . . . . . . . . . . .
Serial Data Communications 1F-10. . . . . . . . . . . . . . .
Euro On-Board Diagnostic (EOBD) 1F-10. . . . . . . . .
Comprehensive Component Monitor Diagnostic
Operation 1F-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Common EOBD Terms 1F-11. . . . . . . . . . . . . . . . . . . .
DTC Types 1F-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reading Diagnostic Trouble Codes 1F-13. . . . . . . . .
Primary System-Based Diagnostics 1F-15. . . . . . . . Diagnostic Information and Procedures 1F-17. . . .
System Diagnosis 1F-17. . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Aids 1F-17. . . . . . . . . . . . . . . . . . . . . . . . . .
Idle Learn Procedure 1F-17. . . . . . . . . . . . . . . . . . . . .
Euro On-Board Diagnostic (EOBD) System
Check 1F-18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ECM Output Diagnosis 1F-20. . . . . . . . . . . . . . . . . . . .
Multiple ECM Information Sensor DTCs Set 1F-21. .
Engine Cranks But Will Not Run 1F-25. . . . . . . . . . . .
No Malfunction Indicator Lamp 1F-30. . . . . . . . . . . . .
Malfunction Indicator Lamp On Steady 1F-32. . . . . .
Fuel System Diagnosis 1F-34. . . . . . . . . . . . . . . . . . . .
Fuel Pump Relay Circuit Check 1F-36. . . . . . . . . . . .
Main Relay Circuit Check 1F-38. . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure Check 1F-40. . . . . . . . . .
Idle Air Control System Check 1F-42. . . . . . . . . . . . .
Ignition System Check 1F-45. . . . . . . . . . . . . . . . . . . .
Engine Cooling Fan Circuit Check 1F-48. . . . . . . . . .
Data Link Connector Diagnosis 1F-52. . . . . . . . . . . . .
Fuel Injector Balance Test 1F-54. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code Diagnosis 1F-55. . . . . . . .
Clearing Trouble Codes 1F-55. . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Codes 1F-55. . . . . . . . . . . . . . . . .
DTC P0107 Manifold Absolute Pressure Sensor
Low Voltage 1F-58. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0108 Manifold Pressure Sensor High
Voltage 1F-62. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0112 Intake Air Temperature Sensor Low
Voltage 1F-66. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0113 Intake Air Temperature Sensor High
Voltage 1F-68. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0117 Engine Coolant Temperature Sensor
Low Voltage 1F-72. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0118 Engine Coolant Temperature Sensor
High Voltage 1F-74. . . . . . . . . . . . . . . . . . . . . . . . . . .

ENGINE CONTROLS 1F–3
DAEWOO M-150 BL2
DTC P1628 Immobilizer No Successful
Communication 1F-270. . . . . . . . . . . . . . . . . . . . . . .
DTC P1629 Immovilizer Wrong Computation 1F-272
DTC P0656 Fuel Level Gauge Circuit Fault 1F-274.
DTC P1660 Malfunction Indicator Lamp (MIL)
High Voltage 1F-276. . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P1661 Malfunction Indicator Lamp (MIL)
Low Voltage 1F-278. . . . . . . . . . . . . . . . . . . . . . . . . .
Symptom Diagnosis 1F-280. . . . . . . . . . . . . . . . . . . . . .
Important Preliminary Checks 1F-280. . . . . . . . . . . . .
Intermittent 1F-281. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hard Start 1F-283. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Surges or Chuggles 1F-286. . . . . . . . . . . . . . . . . . . . .
Lack of Power, Sluggishness or Sponginess 1F-288
Detonation/Spark Knock 1F-290. . . . . . . . . . . . . . . . . .
Hesitation, Sag, Stumble 1F-292. . . . . . . . . . . . . . . . .
Cuts Out, Misses 1F-294. . . . . . . . . . . . . . . . . . . . . . . .
Poor Fuel Economy 1F-296. . . . . . . . . . . . . . . . . . . . . .
Rough, Unstable, or Incorrect Idle, Stalling 1F-297. .
Excessive Exhaust Emissions or Odors 1F-300. . . .
Dieseling, Run-on 1F-302. . . . . . . . . . . . . . . . . . . . . . .
Backfire 1F-303. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance and Repair 1F-304. . . . . . . . . . . . . . . . . .
On-Vehicle Service 1F–304 . . . . . . . . . . . . . . . . . . . . . . .
Fuel Pump 1F–304 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Pressure Regulator 1F-305. . . . . . . . . . . . . . . . .
Fuel Filter 1F-306. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Tank 1F-307. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Rail and Injectors 1F-308. . . . . . . . . . . . . . . . . . .
Evaporator Emission Canister 1F-309. . . . . . . . . . . . . Evaporator Emission Canister Purge
Solenoid 1F-310. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure (MAP) Sensor 1F-310. .
Throttle Body 1F-311. . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature (ECT) Sensor 1F-312.
Intake Air Temperature (ECT) Sensor 1F-313. . . . . .
Oxygen Sensor (O2S 1) 1F-314. . . . . . . . . . . . . . . . . .
Heated Oxygen Sensor (HO2S 2) 1F-314. . . . . . . . .
Electric Exhaust Gas Recirculation (EEGR)
Valve 1F-315. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Knock Sensor 1F-315. . . . . . . . . . . . . . . . . . . . . . . . . . .
Electronic Ignition (EI) System Ignition Coil 1F-316.
Crankshaft Position (CKP) Sensor 1F-316. . . . . . . .
Camshaft Position (CMP) Sensor 1F-317. . . . . . . . . .
Engine Control Module (ECM) 1F-317. . . . . . . . . . . . .
Specifications 1F-319. . . . . . . . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specification 1F-319. . . . . . . . . .
Special Tools 1F-319. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Tools Table 1F-319. . . . . . . . . . . . . . . . . . . . . .
Schematic and Routing Diagrams 1F-320. . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 1 of 5) 1F-320. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 2 of 5) 1F-321. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 3 of 5) 1F-322. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 4 of 5) 1F-323. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 5 of 5) 1F-324. . . . . . . . . . . . . . . . . . . .

1F–4 ENGINE CONTROLS
DAEWOO M-150 BL2
DESCRIPTION AND OPERATION
IGNITION SYSTEM OPERATION
This ignition system does not use a conventional distrib-
utor and coil. It uses a crankshaft position sensor input
to the Engine Control Module (ECM). The ECM then de-
termines Electronic Spark Timing (EST) and triggers the
electronic ignition system ignition coil.
This type of distributorless ignition system uses a “waste
spark’’ method of spark distribution. Each cylinder is in-
dividural with coil per cylinder.
These systems use the EST signal from the ECM to
control the EST. The ECM uses the following informa-
tion:

Engine load (manifold pressure or vacuum).

Atmospheric (barometric) pressure.

Engine temperature.

Intake air temperature.

Crankshaft position.

Engine speed (rpm).
ELECTRONIC IGNITION SYSTEM
IGNITION COIL
The Electronic Ignition (EI) system ignition coil is
mounted near on the cylinder head.
A terminals of the EI system ignition coil provides the
spark for each spark plug. The EI system ignition coil is
not serviceable and must be replaced as an assembly.
CRANKSHAFT POSITION SENSOR
This Electronic Ignition (EI) system uses a magnetic
crankshaft position sensor. This sensor protrudes
through its mount to within approximately 1.3 mm (0.05
inch) of the crankshaft reluctor. The reluctor is a special
wheel attached to the crankshaft with 58 slots machined
into it, 57 of which are equally spaced in 6-degree inter-
vals. The last slot is wider and serves to generate a
“sync pulse.” As the crankshaft rotates, the slots in the
reluctor change the magnetic field of the sensor, creat-
ing an induced voltage pulse. The longer pulse of the
58th slot identifies a specific orientation of the crank-
shaft and allows the Engine Control Module (ECM) to
determine the crankshaft orientation at all times. The
ECM uses this information to generate timed ignition
and injection pulses that it sends to the ignition coils and
to the fuel injectors.
CAMSHAFT POSITION SENSOR
The Camshaft Position (CMP) sensor sends a CMP sig-
nal to the Engine Control Module (ECM). The ECM uses
this signal as a “sync pulse” to trigger the injectors in the
proper sequence. The ECM uses the CMP signal to indi-
cate the position of the #1 piston during its power stroke.
This allows the ECM to calculate true sequential fuel in-jection mode of operation. If the ECM detects an incor-
rect CMP signal while the engine is running, Diagnostic
Trouble Code (DTC) P0341 will set. If the CMP signal is
lost while the engine is running, the fuel injection system
will shift to a calculated sequential fuel injection mode
based on the last fuel injection pulse, and the engine will
continue to run. As long as the fault is present, the en-
gine can be restarted. It will run in the calculated se-
quential mode with a 1-in-6 chance of the injector
sequence being correct.
IDLE AIR SYSTEM OPERATION
The idle air system operation is controlled by the base
idle setting of the throttle body and the Idle Air Control
(IAC) valve.
The Engine Control Module (ECM) uses the IAC valve to
set the idle speed dependent on conditions. The ECM
uses information from various inputs, such as coolant
temperature, manifold vacuum, etc., for the effective
control of the idle speed.
FUEL CONTROL SYSTEM
OPERATION
The function of the fuel metering system is to deliver the
correct amount of fuel to the engine under all operating
conditions. The fuel is delivered to the engine by the in-
dividual fuel injectors mounted into the intake manifold
near each cylinder.
The main fuel control sensors are the Manifold Absolute
Pressure (MAP) sensor, the oxygen sensor (O2S), and
the heated oxygen sensor (HO2S).
The MAP sensor measures or senses the intake man-
ifold vacuum. Under high fuel demands, the MAP sensor
reads a low vacuum condition, such as wide open
throttle. The Engine Control Module (ECM) uses this in-
formation to enrich the mixture, thus increasing the fuel
injector on-time, to provide the correct amount of fuel.
When decelerating, the vacuum increases. This vacuum
change is sensed by the MAP sensor and read by the
ECM, which then decreases the fuel injector on-time
due to the low fuel demand conditions.
The O2S is located in the exhaust manifold. The HO2S
is located in the exhaust pipe. The oxygen sensors indi-
cate to the ECM the amount of oxygen in the exhaust
gas, and the ECM changes the air/fuel ratio to the en-
gine by controlling the fuel injectors. The best air/fuel ra-
tio to minimize exhaust emissions is 14.7:1, which
allows the catalytic converter to operate most efficiently.
Because of the constant measuring and adjusting of the
air/fuel ratio, the fuel injection system is called a “closed
loop” system.
The ECM uses voltage inputs from several sensors to
determine how much fuel to provide to the engine. The

1F–10 ENGINE CONTROLS
DAEWOO M-150 BL2
fuels use alcohol to increase the octane rating of the
fuel. Although alcohol-enhanced fuels may raise the oc-
tane rating, the fuel’s ability to turn into vapor in cold
temperatures deteriorates. This may affect the starting
ability and cold driveability of the engine.
Low fuel levels can lead to fuel starvation, lean engine
operation, and eventually engine misfire.
Non-OEM Parts
The EOBD system has been calibrated to run with Origi-
nal Equipment Manufacturer (OEM) parts. Something
as simple as a high performance-exhaust system that
affects exhaust system back pressure could potentially
interfere with the operation of the Electric Exhaust Gas
Recirculation (EEGR) valve and thereby turn on the
MIL. Small leaks in the exhaust system near the heated
oxygen sensor (HO2S) can also cause the MIL to turn
on.
Aftermarket electronics, such as cellular phones, ster-
eos, and anti-theft devices, may radiate Electromagnet-
ic Interference (EMI) into the control system if they are
improperly installed. This may cause a false sensor
reading and turn on the MIL.
Environment
Temporary environmental conditions, such as localized
flooding, will have an effect on the vehicle ignition sys-
tem. If the ignition system is rain-soaked, it can tempo-
rarily cause engine misfire and turn on the MIL.
Vehicle Marshaling
The transportation of new vehicles from the assembly
plant to the dealership can involve as many as 60 key
cycles within 2 to 3 miles of driving. This type of opera-
tion contributes to the fuel fouling of the spark plugs and
will turn on the MIL with a set DTC P0300.
Poor Vehicle Maintenance
The sensitivity of the EOBD will cause the MIL to turn on
if the vehicle is not maintained properly. Restricted air fil-
ters, fuel filters, and crankcase deposits due to lack of oil
changes or improper oil viscosity can trigger actual ve-
hicle faults that were not previously monitored prior to
EOBD. Poor vehicle maintenance can not be classified
as a “non-vehicle fault,” but with the sensitivity of the
EOBD, vehicle maintenance schedules must be more
closely followed.
Severe Vibration
The Misfire diagnostic measures small changes in the
rotational speed of the crankshaft. Severe driveline
vibrations in the vehicle, such as caused by an exces-
sive amount of mud on the wheels, can have the same
effect on crankshaft speed as misfire and, therefore,
may set DTC P0300.
Related System Faults
Many of the EOBD system diagnostics will not run if the
Engine Control Module (ECM) detects a fault on a re-
lated system or component. One example would be thatif the ECM detected a Misfire fault, the diagnostics on
the catalytic converter would be suspended until the
Misfire fault was repaired. If the Misfire fault is severe
enough, the catalytic converter can be damaged due to
overheating and will never set a Catalyst DTC until the
Misfire fault is repaired and the Catalyst diagnostic is al-
lowed to run to completion. If this happens, the custom-
er may have to make two trips to the dealership in order
to repair the vehicle.
SERIAL DATA COMMUNICATIONS
Keyword 2000 Serial Data
Communications
Government regulations require that all vehicle
manufacturers establish a common communication sys-
tem. This vehicle utilizes the “Keyword 2000” commu-
nication system. Each bit of information can have one of
two lengths: long or short. This allows vehicle wiring to
be reduced by transmitting and receiving multiple sig-
nals over a single wire. The messages carried on Key-
word 2000 data streams are also prioritized. If two
messages attempt to establish communications on the
data line at the same time, only the message with higher
priority will continue. The device with the lower priority
message must wait. The most significant result of this
regulation is that it provides scan tool manufacturers
with the capability to access data from any make or
model vehicle that is sold.
The data displayed on the other scan tool will appear the
same, with some exceptions. Some scan tools will only
be able to display certain vehicle parameters as values
that are a coded representation of the true or actual val-
ue. On this vehicle, the scan tool displays the actual val-
ues for vehicle parameters. It will not be necessary to
perform any conversions from coded values to actual
values.
EURO ON-BOARD DIAGNOSTIC
(EOBD)
Euro On-Board Diagnostic Tests
A diagnostic test is a series of steps, the result of which
is a pass or fail reported to the diagnostic executive.
When a diagnostic test reports a pass result, the diag-
nostic executive records the following data:

The diagnostic test has been completed since the last
ignition cycle.

The diagnostic test has passed during the current
ignition cycle.

The fault identified by the diagnostic test is not cur-
rently active.
When a diagnostic test reports a fail result, the diagnos-
tic executive records the following data:

The diagnostic test has been completed since the last
ignition cycle.

1F–54 ENGINE CONTROLS
DAEWOO M-150 BL2
FUEL INJECTOR BALANCE TEST
A fuel injector tester is used to energize the injector for a
precise amount of time, thus spraying a measured
amount of fuel into the intake manifold. This causes adrop in the fuel rail pressure that can be recorded and
used to compare each of the fuel injectors. All of the fuel
injectors should have the same pressure drop.
Fuel Injector Balance Test Example
Cylinder123
First Reading380 kPa
(55 psi)380 kPa
(55 psi)380 kPa
(55 psi)
Second Reading215 kPa
(31 psi)201 kPa
(29 psi)230 kPa
(33 psi)
Amount Of Drop165 kPa
(24 psi)179 kPa
(26 psi)151 kPa
(22 psi)
Average Range: 156-176 kPa
(22.5-25.5 psi)Injector OKFaulty Injector –
Too Much
Pressure DropFaulty Injector –
Too Little
Pressure Drop
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 pres-
sure before disconnecting the fuel lines.
Caution: Do not pinch or restrict fuel lines. Damage
to the lines could cause a fuel leak, resulting in pos-
sible fire or personal injury.
Notice: In order to prevent flooding of the engine, do not
perform the Injector Balance Test more than once (in-
cluding any retest on faulty fuel injectors) without run-
ning the engine.
Test
Notice: An engine cool down period of 10 minutes is
necessary in order to avoid irregular readings due to hot
soak fuel boiling.
1. Connect the fuel pressure gauge carefully to avoid
any fuel spillage.
2. The fuel pump should run about 2 seconds after the
ignition is turned to the ON position.
3. Insert a clear tube attached to the vent valve of the
fuel pressure gauge into a suitable container.
4. Bleed the air from the fuel pressure gauge and hose
until all of the air is bled from the fuel pressure gauge.
5. The ignition switch must be in the OFF position at
least 10 seconds in order to complete the electronic
control module (ECM) shutdown cycle.6. Turn the ignition ON in order to get the fuel pressure
to its maximum level.
7. Allow the fuel pressure to stabilize and then record
this initial pressure reading. Wait until there is no
movement of the needle on the fuel pressure gauge.
8. Follow the manufacturer’s instructions for the use of
the adapter harness. Energize the fuel injector test-
er once and note the fuel pressure drop at its lowest
point. Record this second reading. Subtract it from
the first reading to determine the amount of the fuel
pressure drop.
9. Disconnect the fuel injector tester from the fuel in-
jector.
10. After turning the ignition ON, in order to obtain maxi-
mum pressure once again, make a connection at
the next fuel injector. Energize the fuel injector test-
er and record the fuel pressure reading. Repeat this
procedure for all the injectors.
11. Retest any of the fuel injectors that the pressure
drop exceeds the 10 kPa (1.5 psi) specification.
12. Replace any of the fuel injectors that fail the retest.
13. If the pressure drop of all of the fuel injectors is with-
in 10 kPa (1.5 psi), then the fuel injectors are flowing
normally and no replacement should be necessary.
14. Reconnect the fuel injector harness and review the
symptom diagnostic tables.

ENGINE CONTROLS 1F–107
DAEWOO M-150 BL2
DTC P0171 – Fuel Trim System Too Lean
StepActionValue(s)YesNo
1
Perform an Euro On-Board Diagnostic (EOBD)
System Check.
Is the system check complete?
–
Go to Step 2
Go to
“On-Board
Diagnostic
System Check”
2
1. Install the scan tool to the Data Link Connector
(DLC).
2. Turn the ignition ON.
Are any component related Diagnostic Trouble
Codes (DTCs) set?
–Go to
Applicable DTC
table
Go to Step 3
3
With the engine running, operate the vehicle until the
LOOP STATUS indicates closed.
Is the Long Term Fuel Trim value below the
specified value?
–22%Go to Step 4Go to Step 5
4
1. Turn the ignition switch ON, with the engine OFF.
2. Review the Freeze Frame data and note the
parameters.
3. Operate the vehicle within the Freeze Frame
conditions and Conditions for Setting The DTC as
noted.
Does the Long Term Fuel Trim value go below the
specified value while operating under the specified
conditions?
–22%Go to Step 16Go to Step 5
5
Visually/physically check the following items:

Vacuum hoses for splits, kinks and improper
connections.

Crankcase ventilation oil/air separator for proper
installation.

Exhaust system for corrosion, leaks, loose or
missing hardware.

Oxygen sensor (O2S) is installed securely and
the pigtail harness is not contacting exhaust
manifold or engine.

Fuel for excessive water, alcohol, or other
contaminants.

Engine Control Module (ECM) and sensor
grounds are clean, tight, and in their proper
locations.
Do any of the above checks isolate a condition
requiring repair?
–
Go to Step 7Go to Step 6
6
1. Disconnect the Manifold Absolute Pressure
(MAP) sensor electrical connector.
2. Operate the vehicle in Closed Loop while
monitoring the Long Term Fuel Trim value.
Is the Long Term Fuel Trim value below the
specified value?
–22%Go to Step 15Go to Step 9
7
1. Repair the malfunction found in Step 5.
2. Recheck the Long Term Fuel Trim value while
operating the engine.
Is the Long Term Fuel Trim value below the
specified value?
–22%Go to Step 8Go to Step 9
8
Lean condition is not present.
Does a driveability problem exist?
–
Go to
“Symptom
Diagnosis”
Go to Step 16

2A–2 SUSPENSION DIAGNOSIS
DAEWOO M-150 BL2
Condition Probable Cause Correction
Car Lead/Pull
Mismatched or uneven tires.
Replace the tires.

A broken or a sagging coil spring.
Replace the coil spring.

A improperly radial tire lateral force.
Check the wheel alignment.

Switch the tire and wheel assemblies.

Replace the tires as needed.

The front–wheel alignment is
out–of–align.
Align the front wheels.

Off–center steering gear.
Reseat the pinion valve assembly.

Replace the pinion valve assembly as
needed.

Front–brake dragging.
Adjust the front brakes.
Abnormal or Excessive
Tire Wear
The front–wheel and rear–wheel
alignment is out–of–align.
Align the front and the rear wheels.

Excessive toe.
Adjust the toe.

A broken or a sagging coil spring.
Replace the coil spring.

Out–of–balance tires.
Balance the tires.

Worn strut dampeners.
Replace the strut dampeners.

A failure to rotate tires.
Rotate the tires.

Replace the tires as needed.

Overloaded vehicle.
Maintain the proper load weight.

Low tire inflation.
Inflate the tires to the proper pressure.
Scuffed Tires
Incorrect toe.
Adjust the toe.

A twisted or a bent suspension arm.
Replace the suspension arm.
Wheel Tramp
An out–of–balance tire or wheel.
Balance the tire or the wheel.

Improper strut dampener action.
Replace the strut dampeners.
Shimmy, Shake, or
An out–of–balance tire or wheel.
Balance the tire or the wheel.
Vibration
Excessive wheel hub runout.
Measure the hub flange runout.

Replace the hub as needed.

Excessive brake drum or brake rotor
imbalance.
Adjust the brakes.

Replace the brake rotor or the brake
drum as needed.

Worn tie rod ends.
Replace the tie rod ends.

Wheel trim imbalance.
Balance the wheel.

A worn ball joint.
Replace the control arm and ball joint
assembly.

Excessive wheel runout.
Measure the wheel runout.

Replace the wheel as needed.

Excessive loaded radial runout on the
tire and wheel assembly.
Match–mount the tire and wheel
assembly.

4A –4 HYDRAULIC BRAKES
DAEWOO M-150 BL2
DIAGNOSITIC INFORMATION AND PROCEDURES
BRAKE SYSTEM TESTING
(Left–Hand Drive Shown, Right–Hand
Drive Similar)
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:

Tires having unequal contact and grip of the road will
cause unequal braking. Tires must be equally in-
flated, and the tread pattern of the right and the left
tires must be approximately equal.

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.

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 pres-
sure 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
leaking. Perform a visual check to confirm any sus-
pected leaks.
Check the master cylinder fluid level. While a slight drop
in the reservoir level results from normal lining wear, an
abnormally low level indicates a leak in the system. The
hydraulic system may be leaking either internally or ex-
ternally. Refer to the procedure below to check the mas-
ter cylinder. Also, the system may appear to pass this
test while still having a slight leak. If the fluid level is nor-
mal, check the vacuum booster pushrod length. If an in-
correct pushrod length is found, adjust or replace the
rod.Check the master cylinder using the following proce-
dure:

Check for a cracked master cylinder casting or brake
fluid leaking around the master cylinder. Leaks are in-
dicated only if there is at least one drop of fluid. A
damp condition is not abnormal.

Check for a binding pedal linkage and for an incorrect
pushrod length. If both of these parts are in satisfac-
tory condition, disassemble the master cylinder 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 rub-
ber 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 evi-
denced by swollen wheel cylinder piston seals on the
drum brake wheels.
If rubber deterioration is evident, disassemble all the hy-
draulic parts and wash the parts with alcohol. Dry these
parts with compressed air before reassembly to keep al-
cohol 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
excessive fluid is found, replace the linings.
If the master cylinder piston seals are in satisfactory
condition, 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 cylin-
der, and bleed the system. Refer to “Manual 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 cover, and for leaks or blisters. Inspect the hoses
for proper routing and mounting. A brake hose that rubs
on a suspension 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 neces-
sary.