ENGINE CONTROLS 1F – 499
DAEWOO V–121 BL4
S The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
An intermittent problem may be caused by a poor connec-
tion, rubbed–through wire insulation, or a wire that is bro-
ken inside the insulation.
VSS signal circuit should be thoroughly checked for the
following conditions:
S Backed–out terminals
S Improper mating
S Broken locks
S Improperly formed
S Damaged terminals
S Poor terminal–to–wire connection
S Physical damage to the wiring harness
Ensure the VSS is correctly tightened with proper torque
to the transmission housing.
Refer to ”Intermittents”in this section.
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Table.
1. The On–Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
2. The permanent magnet generator only produces a
signal if the drive wheels are turning greater than 5
mph (8 km/h). This step determines if DTC P0502
is the result of a hard failure or an intermittent con-
dition.
3. Proper engine loads cannot be achieved in a shop
environment to properly run the vehicle within the
Freeze Frame Data conditions. It will be necessary
to drive the vehicle on the road to obtain the proper
engine loads.
4. This step verifies that the ECM is receiving a signal
from the vehicle speed sensor.
5. Refer to service bulletin information for the latest
calibration update.
6. Refer to the latest Techline information for program-
ming procedures.
8. A resistance reading that is higher than the speci-
fied value indicates that the VSS circuitry is open.
10. If the displayed resistance is less than the 1300
ohms, the VSS high and low circuits are shorted
together.
11. This checks the resistance of the VSS if no opens
or shorts were found on the VSS high and low cir-
cuits.
13. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
DTC P0502 – Vehicle Speed Sensor No Signal (Engine Side)
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check performed?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
2Notice : Running the vehicle in gear with the wheels
hanging down at full travel will damage the drive
axles.
1. Install a scan tool to the Data Link Connector
(DLC).
2. Raise the drive wheels.
3. Support the lower control arms so that the
drive axles are in a horizontal (straight) posi-
tion.
4. Start the engine and allow to idle in gear.
Does the scan tool display vehicle speed above the
specific value?0 mphGo to Step 3Go to Step 4
ENGINE CONTROLS 1F – 633
DAEWOO V–121 BL4
Failed This Ig. (Failed This Ignition)
This message display indicates that the diagnostic test
has failed at least once during the current ignition cycle.
This message will clear when DTCs are cleared or the igni-
tion is cycled.
History
This message display indicates that the DTC has been
stored in memory as a valid fault. A DTC displayed as a
History fault may not mean that the fault is no longer pres-
ent. The history description means that all the conditions
necessary for reporting a fault have been met (maybe
even currently), and the information was stored in the con-
trol module memory.
MIL Requested
This message display indicates that the DTC is currently
causing the MIL to be turned ON. Remember that only
type A and type B DTCs can request the MIL. The MIL re-
quest cannot be used to determine if the DTC fault condi-
tions are currently being experienced. This is because the
diagnostic executive will require up to three trips during
which the diagnostic test passes to turn OFF the MIL.
Not Run Since CI (Not Run Since Cleared)
This message display indicates that the selected diagnos-
tic test has not run since the last time DTCs were cleared.
Therefore, the diagnostic test status (passing or failing) is
unknown. After DTCs are cleared, this message will con-
tinue to be displayed until the diagnostic test runs.
Not Run This Ig. (Not Run This Ignition)
This message display indicates that the selected diagnos-
tic test has not run during this ignition cycle.
Test Ran and Passed
This message display indicates that the selected diagnos-
tic test has done the following:
S Passed the last test.
S Run and passed during this ignition cycle.
S Run and passed since DTCs were last cleared.
If the indicated status of the vehicle is ”Test Ran and
Passed” after a repair verification, the vehicle is ready to
be released to the customer.
If the indicated status of the vehicle is ”Failed This Ignition”
after a repair verification, then the repair is incomplete and
further diagnosis is required.
Prior to repairing a vehicle, status information can be used
to evaluate the state of the diagnostic test, and to help
identify an intermittent problem. The technician can con-
clude that although the MIL is illuminated, the fault condi-
tion that caused the code to set is not present. An intermit-
tent condition must be the cause.
PRIMARY SYSTEM – BASED
DIAGNOSTICS
There are primary system–based diagnostics which eval-
uate system operation and its effect on vehicle emissions.
The primary system–based diagnostics are listed below
with a brief description of the diagnostic function:
Oxygen Sensor Diagnosis
The fuel control Front Heated Oxygen Sensor (HO2S1) is
diagnosed for the following conditions:
S Slow response.
S Response time (time to switch R/L or L/R).
S Inactive signal (output steady at bias voltage
approx. 450 mv).
S Signal fixed high.
S Signal fixed low.
The catalyst monitor Rear Heated Oxygen Sensor
(HO2S2) is diagnosed for the following conditions:
S Heater performance (time to activity on cold start).
S Signal fixed low during steady state conditions or
power enrichment (hard acceleration when a rich-
mixture should be indicated).
S Signal fixed high during steady state conditions or
deceleration mode (deceleration when a lean mix-
ture should be indicated).
S Inactive sensor (output steady at approximately 438
mv).
If the oxygen sensor pigtail wiring, connector or terminal
are damaged, the entire oxygen sensor assembly must be
replaced. Do not attempt to repair the wiring, connector or
terminals. In order for the sensor to function properly, it
must have clean reference air provided to it. This clean air
reference is obtained by way of the oxygen sensor wire(s).
Any attempt to repair the wires, connector or terminals
could result in the obstruction of the reference air and de-
grade oxygen sensor performance.
Misfire Monitor Diagnostic Operation
The misfire monitor diagnostic is based on crankshaft
rotational velocity (reference period) variations. The en-
gine control module (ECM) determines crankshaft rota-
tional velocity using the Crankshaft Position (CKP) sensor
and the Camshaft Position (CMP) sensor. When a cylinder
misfires, the crankshaft slows down momentarily. By mon-
itoring the CKP and CMP sensor signals, the ECM can cal-
culate when a misfire occurs.
For a non–catalyst damaging misfire, the diagnostic will be
required to monitor a misfire present for between
1000–3200 engine revolutions.
For catalyst–damaging misfire, the diagnostic will respond
to misfire within 200 engine revolutions.
Rough roads may cause false misfire detection. A rough
road will cause torque to be applied to the drive wheels and
drive train. This torque can intermittently decrease the
crankshaft rotational velocity. This may be falsely de-
tected as a misfire.
SECTION : 2A
SUSPENSION DIAGNOSIS
TABLE OF CONTENTS
DIAGNOSIS2A–1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Diagnosis 2A–1. . . . . . . . . . . . . . . . . . . . . . . . . Torque Steer 2A–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tapered Roller Bearing 2A–6. . . . . . . . . . . . . . . . . . . . .
DIAGNOSIS
GENERAL DIAGNOSIS
Problems in the steering, the suspension, the tires, and
the wheels involve several systems. Consider all systems
when diagnosing a complaint. Some problems, such as
abnormal or excessive tire wear and scuffed tires, may be
the result of hard driving. Always road test the vehicle first.If possible, do this road test with the customer.
Proceed with the following preliminary checks. Correct
any substandard conditions.
Preliminary Checks
ChecksAction
Inspect the tires for improper pressure and uneven wear.Inflate the tires to the proper pressure.
Inspect the joint from the steering column to the steering
gear for loose connections or wear.Tighten the intermediate shaft pinch bolts. Replace the in-
termediate shaft as needed.
Inspect the front and the rear suspension, the steering
gear, and the linkage for loose or damaged parts.Tighten the front and the rear suspension. Tighten the
steering gear mounting bracket bolts. Tighten the coupling
flange pinch bolts. Replace the front and the rear suspen-
sion as needed. Replace the steering gear as needed. Re-
place the intermediate shaft as needed.
Inspect for out–of–round tires.Perform a free runout test. Match–mount the tires.
Inspect for out–of–balance tires, bent wheels, and worn or
loose wheel bearings.Balance the wheels. Replace the wheels. Replace the
wheel bearings.
Check the power steering pump serpentine belt tension.Tighten the power steering pump serpentine belt.
Inspect the power steering system for leaks. Check the
power steering fluid level.Repair any leaks. Perform a power steering gear test. Add
power steering fluid.
Car Lead/Pull
ChecksAction
Inspect for mismatched or uneven tires.Replace the tires.
Inspect for a broken or a sagging spring.Replace the spring.
Inspect for a radial tire lateral force.Check the wheel alignment. Switch the wheels. Replace
the tires as needed.
Check the front–wheel alignment.Align the front wheels.
Inspect for an off–center steering gear.Reseat the pinion valve assembly. Replace the pinion
valve assembly as needed.
Inspect for front–brake dragging.Adjust the front brakes.
SUSPENSION DIAGNOSIS 2A – 5
DAEWOO V–121 BL4
Steering Wheel Kickback
ChecksAction
Inspect for air in the power steering system.Purge the power steering system of air.
Inspect for a loose steering gear mounting.Tighten the steering gear mounting bracket nuts.
Inspect the joint from the column to the steering gear for
loose connections or wear.Tighten the intermediate shaft pinch bolts. Replace the in-
termediate shaft as needed.
Inspect for loose tie rod ends.Tighten the tie rod ends. Replace the outer tie rods as
needed.
Inspect for loose or worn wheel bearings.Tighten the drive axle nut. Replace the wheel bearings as
needed.
Steering Wheel Surges or Jerks
ChecksAction
Check the hydraulic system. Test the power steering sys-
tem pressure with a gauge.Replace the seals and the hoses as needed.
Inspect for a sluggish steering gear valve.Clean the pinion valve assembly. Replace the pinion valve
assembly as needed.
Inspect for a loose power steering pump serpentine belt.Adjust the power steering pump serpentine belt.
Cupped Tires
ChecksAction
Check the front–wheel and the rear–wheel alignment.Align the front and the rear wheels.
Inspect for worn strut dampeners.Replace the strut dampeners.
Inspect for worn or loose wheel bearings.Tighten the drive axle nut. Replace the wheel bearings as
needed.
Inspect for excessive tire or wheel runout.Match–mount the tires. Replace the tires as needed. Re-
place the wheels as needed.
Inspect for a worn ball joint.Replace the ball joint.
Check the steering gear preload adjustment.Perform a rack bearing preload adjustment.
TORQUE STEER
A degree of torque steer to the right may be experienced
during the use of heavy throttle on some front–wheel drive
cars with drive axles of unequal length. This torque steer
to the right results from the right drive axle being longer
than the left drive axle, which creates a difference in the
drive axle angle. Cars with intermediate shaft assemblies
have axles of almost equal length.
A difference in the drive axle lengths results in more torque
toe–in in the left front wheel. You will notice the torque toe–
in when the vehicle accelerates from a standing start or at
lower speeds.
Inspection Procedure
1. Place a small piece of tape at the top center of the
steering wheel.2. Note the inches of steering wheel deflection re-
quired to keep the vehicle straight during heavy ac-
celeration.
3. Compare this finding with similar cars.
Factors that may cause torque steer to be more apparent
on a particular vehicle include:
S Variations in the tire and wheel assemblies. This
has the most significant effect on torque steer. A
slightly smaller diameter on the right front tire will
increase a right torque lead.
S Large differences in the right and the left front tire
pressure.
S Looseness in the control arm bushings, the tie rod
assemblies, or the steering gear mounting. This
looseness permits a front wheel to pull forward and
toe–in under a torque greater than the wheel on the
opposite side. A loose suspension component may
result in an opposite lead upon deceleration.
2A – 6ISUSPENSION DIAGNOSIS
DAEWOO V–121 BL4
S A high front trim height. This height would increase
the drive axle angle and could cause wobble at
speeds between 24 to 48 km/h (15 to 30 mph).
S Binding or a tight drive axle joint. A tight drive axle
joint or a high front trim height may also cause a
wobble at speeds between 24 to 48 km/h (15 to 30
mph).
S Incorrect, worn, or loose engine mounts causing
adverse drive angles.
Refer to ”General Diagnosis” in this section for actions to
remedy these problems.
Conditions that may produce an effect similar to torque
steer include:
S Incorrect front or rear alignment.
S Frame misalignment or defect.
S Front suspension damage.
S Incorrectly mounted rear crossmember.
TAPERED ROLLER BEARING
Perform the following test to check for looseness in the
hub and bearing assembly on vehicles equipped with rear
disc brakes:
1. Raise and suitably support the vehicle.
2. Remove the rear wheel. Refer to Section 2E, Tires
and Wheels.
3. Remove the brake disc caliper and the brake rotor.
Refer to Section 4E1, Rear Disc Brakes.4. Mount a dial indicator set with a magnetic base to a
control arm or any other stationary part of the ve-
hicle.
5. Push and pull the wheel hub by hand. If the wheel
hub movement exceeds 0.05 mm (0.002 inch), re-
place the wheel bearing. Refer to Section 2D, Rear
Suspension.
6. Install the brake disc caliper and the brake rotor.
Refer to Section 4E1, Rear Disc Brakes.
7. Install the rear wheel. Refer to Section 2E, Tires
and Wheels.
8. Lower the vehicle.
2C – 6IFRONT SUSPENSION
DAEWOO V–121 BL4
BALL JOINT AND KNUCKLE
Ball Joint Inspection
1. Raise the front of the vehicle to allow the front sus-
pension to hang free.
2. Grasp the tire at the top and the bottom.
3. Move the top of the tire in an in–and–out motion.
4. Look for any horizontal movement of the knuckle
relative to the control arm.
5. Ball joints must be replaced under the following
conditions:
S The joint is loose.
S The ball seal is cut.
S The ball stud is disconnected from the knuckle.
S The ball stud is loose at the knuckle.
S The ball stud can be twisted in its socket with
finger pressure.
Ball Stud Inspection
Make sure to check the tightness of the ball stud in the
knuckle boss during each inspection of the ball joint. One
way to inspect the ball stud for wear is to shake the wheel
and feel for movement of the stud end at the knuckle boss.Another way to inspect the ball stud for wear is to check
the fastener torque at the pinch nut. A loose nut can indi-
cate a stressed stud or a hole in the knuckle boss.
Worn or damaged ball joints and knuckles must be re-
placed.
EXCESSIVE FRICTION CHECK
Use the following procedure to check for excessive friction
in the front suspension:
1. Enlist the help of another technician to lift up on the
front bumper, raising the vehicle as high as pos-
sible.
2. Slowly release the bumper, allowing the vehicle to
assume its normal trim height. See ”General Speci-
fications” in this section.
3. Measure the distance from the street level to the
center of the bumper.
4. Push down on the bumper, release slowly, and al-
low the vehicle to assume its normal trim height.
5. Measure the distance from the street level to the
center of the bumper.
6. The difference between the two measurements
should be less than 12.7 mm (0.5 inch). If the differ-
ence exceeds this limit, inspect the control arms,
the struts, and the ball joints for damage or wear.
TIRES AND WHEELS 2E – 3
DAEWOO V–121 BL4
MAINTENANCE AND REPAIR
ON–VEHICLE SERVICE
WHEEL
Removal Procedure
1. Loosen the wheel bolts.
2. Raise and suitably support the vehicle.
3. Remove the wheel bolts.
Notice : Never use heat to loosen a tight wheel. It can
shorten the life of the wheel, the wheel nuts and the wheel
bearings. Excessive force, such as hammering the wheel
or tire, can also cause damage and is not recommended.
Slight tapping of the wheel sidewall with one’s hand or with
a rubber mallet is acceptable.
4. Remove the wheel.
Difficulty in removing the wheels from the vehicle can be
due to foreign material or to a tight fit between the wheel
centerhole and the hub or the rotor. These wheels can be
removed by
5. Retightening the wheel bolts on the affected wheel
and then loosening the wheel bolts by two turns.
6. Lowering the vehicle and rocking it from side to side
as hard as possible, using one or more person’s
body weight to loosen the wheel.
7. Raising the vehicle and removing the wheel.
CAUTION : Do not allow the penetrating oil to get on
the vertical surfaces between the wheel and the drum
(or rotor) because penetrating oil in this area could
cause the wheel to work loose as the vehicle is driven,
resulting in loss of control and an injury accident.
Penetrating oil is not effective in removing tight wheels. If
it is used, however, apply it sparingly and only to the
wheel’s centerhole area.
Installation Procedure
Notice : Before installing the wheels, remove any buildup
of corrosion on the wheel mounting surface and the brake
drum or the rotor mounting surface by scraping and brush-
ing them with a wire brush. Installing the wheels without
good metal–to–metal contact at the mounting surfaces
can cause the wheel nuts to loosen, which can later allow
a wheel to come off while the vehicle is moving. Wheel
bolts must be tightened in sequence and to the proper
torque to avoid bending the wheel, the brake drum or the
rotor.
1. Mount the wheel.
2. Install the wheel bolts in the sequence shown. Do
not tighten the wheel bolts.
3. Lower the vehicle.
Tighten
Tighten the wheel bolts to 100 NSm (74 lb–ft).
TIRES AND WHEELS 2E – 11
DAEWOO V–121 BL4
pacity, diameter, rim width, offset, and mounting configu-
ration. A wheel of improper size or type may affect wheel
and bearing life, brake cooling, speedometer/odometer
calibration, vehicle ground clearance, and tire clearance
to the body and the chassis. The wheel offset is 49 ± 1 mm
(1.93 ± 0.04 inches). Steel wheels may be identified by a
two– or three–letter code stamped into the rim near the
valve stem. Alloy wheels should have the code, the part
number, and the manufacturer ID cast into the back side.
INFLATION O TIRES
The pressure recommended for any vehicle line is careful-
ly calculated to give a satisfactory ride, handling, tread life,
and load–carrying capacity.
Tire pressure should be checked monthly or before any
extended trip. Check the tires when they are cold, after the
vehicle has sat for 3 hours or more, or has been driven less
than 1 mile. Set the tire pressure to the specifications on
the tire label located on the rear face of the driver’s door.
Tire inflation pressure is also given under ”Tire Size and
Pressure Specifications” in this section.
Valve caps or extensions should be on the valves to keep
dust and water out.
For sustained driving at speeds up to 140 km/h (85 mph),
inflate the tires to the pressure recommended on the tire.
Sustained driving at speeds faster than 140 km/h (85mph), even if permitted by law, is not advised unless the
vehicle has special high–speed tires available from many
tire dealers. Tire pressures may increase as much as 41
kPa (6 psi) when the tires are hot.
Higher than recommended tire pressure can cause
S Hard ride.
S Tire bruising or damage.
S Rapid tread wear at the center of the tire.
Lower than recommended pressure can cause
S Tire squeal on turns.
S Hard steering.
S Rapid and uneven wear on the edges of the tread.
S Tire rim bruises and rupture.
S Tire cord breakage.
S High tire temperatures.
Unequal tire pressures on same axle can cause
S Uneven braking.
S Steering lead.
S Reduced handling.
S Swerve on acceleration.
S Torque steer.