ENGINE CONTROLS 1F – 623
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
IGNITION SYSTEM OPERATION
This ignition system does not use a conventional distribu-
tor and coil. It uses a crankshaft position sensor input to
the engine control module (ECM). The ECM then deter-
mines Electronic Spark Timing (EST) and triggers the di-
rect ignition system ignition coil.
This type of distributorless ignition system uses a ”waste
spark” method of spark distribution. Each cylinder is
paired with the cylinder that is opposite it (1–4 or 2–3). The
spark occurs simultaneously in the cylinder coming up on
the compression stroke and in the cylinder coming up on
the exhaust stroke. The cylinder on the exhaust stroke re-
quires very little of the available energy to fire the spark
plug. The remaining energy is available to the spark plug
in the cylinder on the compression stroke.
These systems use the EST signal from the ECM to con-
trol the electronic spark timing. The ECM uses the follow-
ing information:
S Engine load (manifold pressure or vacuum).
S Atmospheric (barometric) pressure.
S Engine temperature.
S Intake air temperature.
S Crankshaft position.
S Engine speed (rpm).
ELECTRONIC IGNITION SYSTEM
IGNITION COIL
The Electronic Ignition (EI) system ignition coil provides
the spark for two spark plugs simultaneously. The EI sys-
tem ignition coil is not serviceable and must be replaced
as an assembly.
CRANKSHAFT POSITION SENSOR
This direct ignition system uses a magnetic crankshaft
position sensor. This sensor protrudes through its mount
to within approximately 0.05 inch (1.3 mm) of the crank-
shaft reluctor. The reluctor is a special wheel attached to
the crankshaft or crankshaft pulley with 58 slots machined
into it, 57 of which are equally spaced in 6 degree intervals.
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, creating an in-
duced voltage pulse. The longer pulse of the 58th slot
identifies a specific orientation of the crankshaft and al-
lows the engine control module (ECM) to determine the
crankshaft orientation at all times. The ECM uses this in-
formation to generate timed ignition and injection pulses
that it sends to the ignition coils and to the fuel injectors.
CAMAHAFT POSITION SENSOR
The Camshaft Position (CMP) sensor sends a CMP sen-
sor signal 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 sensor sig-
nal to indicate the position of the #1 piston during its power
stroke. This allows the ECM to calculate true sequential
fuel injection mode of operation. If the ECM detects an in-
correct CMP sensor signal while the engine is running,
DTC P0341 will set. If the CMP sensor 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 engine can be restarted.
It will run in the calculated sequential 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 tem-
perature, 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 indi-
vidual fuel injectors mounted into the intake manifold near
each cylinder.
The two main fuel control sensors are the Manifold Abso-
lute Pressure (MAP) sensor, the Front Heated Oxygen
Sensor (HO2S1) and the Rear Heated Oxygen Sensor
(HO2S2).
The MAP sensor measures or senses the intake manifold
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 information to ri-
chen 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 de-
creases the fuel injector on–time due to the low fuel de-
mand conditions.
HO2S Sensors
The HO2S sensor is located in the exhaust manifold. The
HO2S sensor indicates to the ECM the amount of oxygen
in the exhaust gas and the ECM changes the air/fuel ratio
to the engine by controlling the fuel injectors. The best air/
fuel ratio to minimize exhaust emissions is 14.7 to 1, which
allows the catalytic converter to operate most efficiently.
ENGINE CONTROLS 1F – 629
DAEWOO V–121 BL4
tentially interfere with the operation of the Exhaust Gas
Recirculation (EGR) valve and thereby turn on the MIL.
Small leaks in the exhaust system near the post catalyst
oxygen sensor can also cause the MIL to turn on.
Aftermarket electronics, such as cellular phones, stereos,
and anti–theft devices, may radiate electromagnetic inter-
ference (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 system.
If the ignition system is rain–soaked, it can temporarily
cause engine misfire and turn on the MIL.
Refueling
A new EOBD diagnostic checks the integrity of the entire
Evaporative (EVAP) Emission system. If the vehicle is re-
started after refueling and the fuel cap is not secured cor-
rectly, the on–board diagnostic system will sense this as
a system fault, turn on the MIL, and set DTC P0440.
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 operation
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 EOBD diagnostics will cause the MIL to
turn on if the vehicle is not maintained properly. Restricted
air filters, fuel filters, and crankcase deposits due to lack
of oil changes or improper oil viscosity can trigger actual
vehicle 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 EOBD
diagnostics, 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 vibra-
tions in the vehicle, such as caused by an excessive
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 controlmodule (ECM) detects a fault on a related
system or component. One example would be that if the
ECM detected a Misfire fault, the diagnostics on the cata-
lytic converter would be suspended until the Misfire fault
was repaired. If the Misfire fault is severe enough, the cat-
alytic converter can be damaged due to overheating andwill never set a Catalyst DTC until the Misfire fault is re-
paired and the Catalyst diagnostic is allowed to run to
completion. If this happens, the customer may have to
make two trips to the dealership in order to repair the ve-
hicle.
SERIAL DATA COMMUNICATIONS
Class II Serial Data Communications
Government regulations require that all vehicle manufac-
turers establish a common communication system. This
vehicle utilizes the ”Class II” communication system. Each
bit of information can have one of two lengths: long or
short. This allows vehicle wiring to be reduced by transmit-
ting and receiving multiple signals over a single wire. The
messages carried on Class II data streams are also priori-
tized. If two messages attempt to establish communica-
tions 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. Themost 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 value. On
this vehicle the scan tool displays the actual values for ve-
hicle parameters. It will not be necessary to perform any
conversions from coded values to actual values.
ON–BOARD DIAGNOSTIC (EOBD)
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 diagnostic
executive records the following data:
S The diagnostic test has been completed since the
last ignition cycle.
S The diagnostic test has passed during the current
ignition cycle.
S The fault identified by the diagnostic test is not cur-
rently active.
When a diagnostic test reports a fail result, the diagnostic
executive records the following data:
S The diagnostic test has been completed since the
last ignition cycle.
S The fault identified by the diagnostic test is current-
ly active.
S The fault has been active during this ignition cycle.
S The operating conditions at the time of the failure.
Remember, a fuel trim Diagnostic Trouble Code (DTC)
may be triggered by a list of vehicle faults. Make use of all
information available (other DTCs stored, rich or lean con-
dition, etc.) when diagnosing a fuel trim fault.
2B – 2IWHEEL ALIGNMENT
DAEWOO V–121 BL4
DIAGNOSIS
TIRE DIAGNOSIS
Irregular and Premature Wear
Irregular and premature tire wear has many causes. Some
of them are incorrect inflation pressures, lack of regular
rotation, poor driving habits, or improper wheel alignment.
If the wheel alignment is reset because of tire wear, always
reset the toe as close to zero degrees as the specification
allows. Refer to ”Rear Toe Adjustment” in this section.
Rotate the tires if:
S The front tire wear is different from the rear.
S The left and right front tire wear is unequal.
S The left and right rear tire wear is unequal.
Check wheel alignment if:
S The left and right front tire wear is unequal.
S The wear is uneven across the tread of either front
tire.
S The front tire treads are scuffed with ”feather”
edges on the side of the tread ribs or blocks.
Tread Wear Indicators
The original equipment tires have built–in tread wear indi-
cators to show when the tires need replacement. These in-
dicators appear as bands when the tire tread depth be-
comes shallow. Tire replacement is recommended when
the indicators appear in three or more grooves at six loca-
tions.
Radial Tire Waddle
Waddle is side–to–side movement at the front or rear of
the vehicle. It is caused by the steel belt not being straight
within the tire, or by excessive lateral runout of the tire or
wheel. It is most noticeable at low speeds, 8 to 48 km/h (5
to 30 mph), but may appear as ride roughness at 80 to 113
km/h (50 to 70 mph).
The vehicle must be road tested to determine which end
of the vehicle has the faulty tire. The rear end of the vehicle
will shake from side to side or ”waddle” if the waddle tire
is on the rear of the vehicle. From the driver’s seat, it feels
as though someone is pushing on the side of the vehicle.
If the faulty tire is on the front of the vehicle, the waddle is
more visual. The front sheet metal appears to be moving
back and forth, and the driver’s seat feels like the pivot
point in the vehicle.
Waddle can be diagnosed using the method of substi–tut-
ing known good tire and wheel assemblies on the problem
vehicle.
1. Road test the vehicle to determine if the waddle is
coming from the front or the rear of the vehicle.
2. Install good tires and wheels from a similar vehicle
in place of those on the offending end of the prob-
lem vehicle. If the source of the waddle is not ob-
vious, change the rear tires.
3. Road test the vehicle. If there is improvement,
install the original tires to find the offending tire. If
there is no improvement, install good tires in place
of all four offending tires.
WHEEL ALIGNMENT 2B – 9
DAEWOO V–121 BL4
REAR TOE ADJUSTMENT
Adjustment Procedure
1. Perform a preliminary inspection before any at-
tempt is made to change or correct the wheel align-
ment factors. Refer to ”Preliminary Inspection” in
this section.
2. Loosen the nuts on the parallel link–to–crossmem-
ber bolts.
3. Rotate the parallel link adjustment bolts until the
preferred rear toe specification is obtained. Refer
to”Wheel Alignment Specifications” in this section
for preferred specifications.
4. Hold the parallel link adjustment bolts and tighten
the parallel link–to–crossmember nuts.
Tighten
Tighten the parallel link–to–crossmember nuts to 90 NSm
(66 lb–ft).
2E – 8ITIRES AND WHEELS
DAEWOO V–121 BL4
TIRE AND WHEEL
MATCH–MOUNTING
The tires and wheels are match–mounted at the assembly
plant. Match–mounting aligns the radially stiffest part of
the tire, or high spot, to the smallest radius, or low spot, of
the wheel.
The high spot of the tire is originally marked by a red paint
mark or an adhesive label on the outboard sidewall.
The low spot of the wheel will be at the location of the valve
stem.
Before dismounting a tire from its wheel, scribe a line on
the tire at the valve stem to assure that it is remounted in
the same position.
Replacement tires that are of original equipment quality
will have their high and low spot marked in the same man-
ner.
TIRE MOUNTING AND DISMOUNTING
Notice : Use a tire–changing machine to mount or dis-
mount the tires. Follow the equipment manufacturer’s in-
structions. Do not use hand tools or tire irons to change
tires. These tools may damage the beads or the wheel rim.
1. Clean the rim bead seats with a wire brush or
coarse steel wool to remove lubricants, old rubber,
and light rust. Before mounting or dismounting a
tire, lubricate the bead area well with an approved
tire lubricant.
CAUTION : To avoid serious injury, do not stand over
the tire when inflating it, because the bead may break
when it snaps over the safety hump. Do not exceed
275 kPa (40 psi) of air pressure in any tire if the beads
are not seated. If 275 kPa (40 psi) of air pressure will
not seat the beads, deflate the tire. Relubricate the
bead and reinflate the tire. Overinflation may cause
the bead to break and cause serious injury.
2. fter mounting the tire, inflate it until the beads are
seated. Never exceed 275 kPa (40 psi) to seat the
beads.
3. Install the valve core and inflate the tire to the prop-
er pressure. Make sure the locating ring outside of
the bead of the tire shows around the rim flanges of
the wheel on both sides. This positioning of the tire
will insure that the bead of the tire is seated.
4F – 22IANTILOCK BRAKE SYSTEM
DAEWOO V–121 BL4
SELF–DIAGNOSTICS
Important : The electronic brake control module (EBCM)
turns the valve relay off when a diagnostic trouble code
(DTC) is set. The scan tool will indicate that the valve relay
is off when it is used to monitor the data list. This is normal
and should not be considered a malfunction.
Important : For safety reasons it is recommended that the
vehicle not be driven with test equipment connected. Ex-
ception : for testing of wheel speeds provided the test reg-
ulations are met.
The EBCM performs system self–diagnostics and can de-
tect and often isolate system malfunctions. When it de-
tects a malfunction, the EBCM sets a DTC that represents
the malfunction, turns ON the ABS and/or the EBD indica-
tors in most instances, and may disable the ABS and/or
the EBD functions as necessary for the duration of the igni-
tion cycle.
Once each ignition cycle, the EBCM performs an automat-
ic test when the vehicle speed > 6 km/h and the brake ped-
al is not actuated or when the vehicle speed > 15 km/h and
the brake pedal is actuated. In the course of this test, the
system cycles each valve solenoid and the pump motor,
along with the necessary relays, to check component op-
eration. If the EBCM detects any malfunctions, it will set
a DTC as described above.
DISPLAYING DTCS
Tools Required
Scan Tool
DTCs can be read through the use of the scan tool.
CLEARING DTCS
Tools Required
Scan Tool
The diagnostic trouble codes (DTCs) in the electronic
brake control module (EBCM) memory are erased:S Use the scan tool ”Clear DTCs” selection.
The method is detailed below. Be sure to verify proper sys-
tem operation and absence of DTCs when the clearing
procedure is completed.
The EBCM will not permit DTC clearing until all DTCs have
been displayed. Also, DTCs cannot be cleared by discon-
necting the EBCM, disconnecting the battery cables, or
turning the ignition switch to LOCK.
Scan Tool Method
The scan tool can clear ABS system DTCs using the mass
storage cartridge.
1. Install the scan tool and the mass storage cartridge.
2. Select ”Fault Memory.”
3. Select ”Clear Fault Memory.”
Clearing the fault memory cannot reset a valve relay which
was shut down when the fault was recognized. Changes
are possible only after the fault has been eliminated and
the next ignition cycle has begun.
INTERMITTENTS AND POOR
CONNECTIONS
As with most electronic systems, intermittent malfunctions
may be difficult to diagnose accurately. The following is a
method to try to isolate an intermittent malfunction, espe-
cially in wheel speed circuitry.
If an ABS malfunction occurs, the ABS indicator will illumi-
nate during the ignition cycle in which the malfunction was
detected. If it is an intermittent problem which seems to
have corrected itself (ABS indicator off), a history DTC will
be stored. Also stored will be the history data of the DTC
at the time the malfunction occurred. Use the scan tool
modular diagnostic system to read ABS history data.
Most intermittents are caused by faulty electrical connec-
tions or wiring, although a sticking relay or solenoid can oc-
casionally be at fault.
ANTILOCK BRAKE SYSTEM 4F – 51
DAEWOO V–121 BL4
Diagnostic Aids
DTC C0245 may be set by running the scan tool auto test
if the throttle angle readings are not updating while in the
data list mode. If this is the case, clear the DTCs, discon-
nect the scan tool, and road test the vehicle to at least 12
km/h (7 mph) to see if the DTC resets.
Check the toothed wheels for any large grooves, gouges,
marks, etc. that might influence the tooth’s signal at the
wheel speed sensor. Also check for a buildup of foreignmaterial in the gaps between teeth in the toothed wheel,
this material may cause this malfunction.
A badly worn hub/bearing assembly may cause this mal-
function. The wheel speed sensor–to–toothed wheel air
gap may change excessively due to bearing play.
If an improper rear hub assembly or front outer constant
velocity joint is installed, one with a toothed wheel contain-
ing the incorrect number of teeth, this DTC can set. Be
sure that the front and the rear toothed wheel have 47 and
29 teeth.
DTC C0245 – Wheel Speed Sensor Frequency Error
StepActionValue(s)YesNo
1Visually inspect the wiring for the front wheel speed
sensors.
Is there any damage?–Go to Step 2Go to Step 3
2Check that the correct outer constant velocity (CV)
joints are installed on the vehicle. The front speed
rings have 47 teeth and the rear speed rings have 29
theeth.
Is the repair complete?–System OK–
3Check fuse EF2 in the engine fuse block.
Is one of these incorrect?–Go to Step 4Go to Step 5
4Replace the incorrect outer CV joint with the proper
unit.
Is the repair complete?–System OK–
51. Disconnect the wheel speed sensor harnesses
from the wheel speed sensor connectors.
2. Measure the wheel speed sensor resistance at
the wheel speed sensor connector terminals.
Does the resistance fall within the specified values
for both wheel speed sensors?1280–1920 WGo to Step 7Go to Step 6
6Replace the faulty wheel speed sensor.
Is the repair complete?–System OK–
71. Disconnect ABS control module connector.
2. Check each wheel speed sensor harness for a
short circuit between its wires with a digital
ohmmeter attached to the two terminals at the
harness side of the wheel speed sensor con-
nector.
3. Also check each wheel speed sensor harness
wire for a short to ground from the connector
terminals.
Is there any short circuit in either wheel speed sen-
sor harness?–Go to Step 8Go to Step 9
8Repair the short circuit in the wiring or from a wiring
harness to ground.
Is the repair complete?–System OK–
5A2 – 60IAISIN AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
DTC P0722 Output Shaft Speed (OSS) sensor Circuit No Signal
StepActionValue(s)YesNo
11. Turn the ignition OFF.
2. Install the Scan tool.
3. With the engine OFF, turn the ignition switch to
the ON position.
4. Select Store Freeze Frame/Failure Records
from the Diagnostic Trouble Codes Information
menu.
5. Store Freeze Frame/Failure Records.
6. Select Clear DTC Information from the Diag-
nostic Trouble Codes Information menu.
7. Clear DTC Information.
8. Perform one vehicle drive cycle.
Is the Malfunction Indicator Lamp (MIL) ON?–Go to Step 2Repair the tem-
porary connec-
tion failure of
connector (Re-
fer to ”Wiring
Harness and
Connector In-
spection” in this
section.)
21. Select Request DTC by Status from the Diag-
nostic Trouble Codes Information menu.
2. Request DTC by Status.
Is DTC P0722 displayed?–Go to Step 3Repair the tem-
porary connec-
tion failure of
connector (Re-
fer to ”Wiring
Harness and
Connector In-
spection” in this
section.)
31. Turn the ignition OFF.
2. Inspect the voltage between vehicle harness
and the Output Shaft Speed (OSS) sensor.
3. Disconnect the connector (X–1) of the vehicle
harness.
4. Connect the voltmeter to monitor the voltage
between terminal B25 and ground.
5. Turn ignition ON and lift up the vehicle.
6. Check the voltage change from approximately
0 v to 12 v when the wheel is turned slowly.
Does the measurement change within the specified
value?0–12 vGo to Step 4Go to Step 5
41. Estimate the failure of between the vehicle wir-
ing harness connector and TCM.
2. Inspect the connector. Refer to ”Wiring Har-
ness and Connector Inspection” in this section.
3. Inspect the connection condition between the
connectors (C–1).
Is the connection condition OK?–Go to Step 6Repair the wir-
ing harness
connectors.
51. Estimate the failure of T/M wire or between the
connectors of OSS sensor.
2. Inspect the OSS sensor. Refer to ”Unit Inspec-
tion” in this section
Is the condition of OSS sensor OK?–Go to Step 7Replace the
OSS sensor