tran DAEWOO LACETTI 2004 Service Manual PDF

1F – 274IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0601
ENGINE CONTROL MODULE CHECKSUM ERROR
Circuit Description
The engine control module (ECM) is the control center of
the fuel injection system. It constantly looks at the informa-
tion from various sensors, and controls the systems that
after vehicle performance. The ECM also performs the
diagnostic function of the system. It can recognize opera-
tional problems, alert the driver through the Malfunction In-
dicator Lamp (MIL), and store a Diagnostic Trouble Code
(DTC) or DTCs which identify the problem areas to aid the
technician in making repairs. An electrically erasable pro-
grammable read only memory (EEPROM) is used to
house the program information and the calibrations re-
quired for engine, transaxle, transaxle diagnostics opera-
tion. The ECM uses a value called a checksum for error
detection of the software. The checksum is a value that is
equal to all the numbers in the software added together.
The ECM adds all the values in the software and if that val-
ue does not equal the checksum value, a checksum error
is indicated.Conditions for Setting the DTC
S The ECM detects incorrect checksum.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after four consecutive ignition
cycle 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.
DTC P0601 – Engine Control Module Checksum Error
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the system check complete?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
2Replace the engine control module(ECM).
Is the replacement complete?–Go to Step 3–
31. Using the scan tool, clear the DTCs.
2. Start the engine and idle at normal operating
temperature.
3. Operate the vehicle within the conditions for
setting this DTC ad specified in the supporting
text.
Does the scan tool indicate that this diagnostic has
run and passed?–Go to Step 4Go to Step 2
4Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
applicable DTC
tableSystem OK

ENGINE CONTROLS 1F – 275
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0604
ENGINE CONTROL MODULE INTERNAL/EXTERNAL RAM
ERROR
Circuit Description
The engine control module (ECM) is the control center of
the fuel injection system. It constantly looks at the informa-
tion from various sensors, and controls the systems that
after vehicle performance. The ECM also performs the
diagnostic function of the system. It can recognize opera-
tional problems, alert the driver through the Malfunction In-
dicator Lamp (MIL), and store a Diagnostic Trouble Code
(DTC) or DTCs which identify the problem areas to aid the
technician in making repairs. An electrically erasable pro-
grammable read only memory (EEPROM) is used to
house the program information and the calibrations re-
quired for engine, transaxle, transaxle diagnostics opera-
tion. The ECM uses a value called a checksum for error
detection of the software. The checksum is a value that is
equal to all the numbers in the software added together.
The ECM adds all the values in the software and if that val-
ue does not equal the checksum value, a checksum error
is indicated.
Conditions for Setting the DTCS The ECM detects an internal or external Random
Acess Memory (RAM) error.
Action Taken When the DTCs Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
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.
DTC P0604 – Engine Control Module Internal/External RAM Error
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the system check complete?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
2Replace the engine control module(ECM).
Is the replacement complete?–Go to Step 3–
31. Using the scan tool, clear the DTCs.
2. Start the engine and idle at normal operating
temperature.
3. Operate the vehicle within the conditions for
setting this DTC ad specified in the supporting
text.
Does the scan tool indicate that this diagnostic has
run and passed?–Go to Step 4Go to Step 2
4Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
applicable DTC
tableSystem OK

1F – 276IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0605
ENGINE CONTROL MODULE INMVY WRITE ERROR
Circuit Description
The engine control module (ECM) is the control center of
the fuel injection system. It constantly looks at the informa-
tion from various sensors, and controls the systems that
after vehicle performance. The ECM also performs the
diagnostic function of the system. It can recognize opera-
tional problems, alert the driver through the Malfunction In-
dicator Lamp (MIL), and store a Diagnostic Trouble Code
(DTC) or DTCs which identify the problem areas to aid the
technician in making repairs. An electrically erasable pro-
grammable read only memory (EEPROM) is used to
house the program information and the calibrations re-
quired for engine, transaxle, transaxle diagnostics opera-
tion. The ECM uses a value called a checksum for error
detection of the software. The checksum is a value that is
equal to all the numbers in the software added together.
The ECM adds all the values in the software and if that val-
ue does not equal the checksum value, a checksum error
is indicated.Conditions for Setting the DTC
S The ECM detects a INMVY write error.
Action Taken When the DTCs Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
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.
DTC P0605 – Engine Control Module INMVY Write Error
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the system check complete?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
2Replace the engine control module(ECM).
Is the replacement complete?–Go to Step 3–
31. Using the scan tool, clear the DTCs.
2. Start the engine and idle at normal operating
temperature.
3. Operate the vehicle within the conditions for
setting this DTC ad specified in the supporting
text.
Does the scan tool indicate that this diagnostic has
run and passed?–Go to Step 4Go to Step 2
4Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
applicable DTC
tableSystem OK

1F – 336IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1628
IMMOBILIZER NO SUCCESSFUL COMMUNICATION
Circuit Description
When the ignition switch is turned to ON, the key tested
by immobilizer anti–theft system. While the key code is be-
ing read by immobilizer control unit or integrated anti–theft
control unit, the engine can start run with any key that will
turn the lock cylinder. the key code is read and compared
with key codes that have been stored in the memory of the
immobilizer control unit. If a valid key is detected, the im-
mobilizer control unit sends a serial data release message
to the Engine Control Module (ECM). Included in the re-
lease message is an identification (ID) code which as-
sures that neither the immobilizer control unit nor the ECM
have been substituted to defeat the system. If the ECM re-
ceives an invalid release message, the ECM performs the
following action:
S Disable the fuel injector circuit.
S Disable the fuel pump circuit.
S Disable the ignition coil.
S A Diagnostic Trouble Code (DTC) will stored if de-
tect communication link failure between the ECM
and immobilizer control unit.Conditions for Setting the DTC
S No safety security strategy allowed.
S Time–out delay has elapsed without successful
communication or a transmission key ON/OFF oc-
curred before a successful communication.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will not illumi-
nate.
S The ECM will store conditions which were present
when the DTC was set as Failure Records data
only.
S This information will not be stored in the Freeze
Frame data.
Conditions for Clearing the MIL/DTC
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.

ENGINE CONTROLS 1F – 345
DAEWOO V–121 BL4
DTCIlluminate MIL Type Description
P0327Knock Sensor Circuit FaultCnlNo
P033658X Crank Position Sensor Extra/Missing PulsesEYe s
P033758X Crank Position Sensor No SignalAYe s
P0341Camshaft Position Sensor RationalityEYe s
P0342Camshaft Position Sensor No SignalAYe s
P0351Ignition Control Circuit A Fault (Cylinder 1 and 4)AYe s
P0352Ignition Control Circuit B Fault (Cylinder 2 and 3)AYe s
P0401Exhaust Gas Recirculation Insufficient FlowCnlNo
P0402Exhaust Gas Recirculation Excessive FlowEYe s
P0404Exhaust Gas Recirculation Open Valve Position ErrorEYe s
P0405Exhaust Gas Recirculation Pintle Position Low VoltageEYe s
P0406Exhaust Gas Recirculation Pintle Position High VoltageEYe s
P0420Catalyst Oxygen Sensor Low EfficiencyAYe s
P0443Evaporative Emission System Purge Solenoid Control CircuitEYe s
P0461Fuel Level StuckCnlNo
P0462Fuel Level Low VoltageCnlNo
P0463Fuel Level High VoltageCnlNo
P0502Vehicle Speed Sensor No Signal (Engine Side)EYe s
P0506Idle Speed rpm Lower Than Desired Idle SpeedEYe s
P0507Idle Speed rpm Higher Than Desired Idle SpeedEYe s
P0532A/C Pressure Sensor Low VoltageCnlNo
P0533A/C Pressure Sensor High VoltageCnlNo
P0562System Voltage Too Low (Engine Side)CnlNo
P0563System Voltage Too High (Engine Side)CnlNo
P0601ECM Checksum Error (Engine Side)AYe s
P0602ECM Reprogram ErrorAYe s
P0607Lower Power Counter ErrorCnlNo
P0700Transaxle Control Module MalfunctionAYe s
P1106Manifold Absolute Pressure Intermittent High VoltageCnlNo
P1107Manifold Absolute Pressure Intermittent Low VoltageCnlNo
P 1111Intake Air Temperature Intermittent High VoltageCnlNo
P1112Intake Air Temperature Intermittent Low VoltageCnlNo
P1114Engine Coolant Temperature Intermittent Low VoltageCnlNo
P1115Engine Coolant Temperature Intermittent High VoltageCnlNo
P1121Throttle Position Sensor Intermittent High VoltageCnlNo
P1122Throttle Position Sensor Intermittent Low VoltageCnlNo
P1133Front Heated Oxygen Sensor (HO2S1) Too Few TransitionsEYe s
P1134Front Heated Oxygen Sensor (HO2S1) Transition RatioEYe s
P1167Front Heated Oxygen Sensor (HO2S1) Rich in Decel Fuel Cut–off (DFCO)AYe s
P1171Fuel Trim System Lean During Power EnrichmentBYe s
P133658X Crank Position Tooth Error Not LearnedAYe s
P1391G Sensor Rough Road RationalityCnlNo

1F – 378IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0133
FRONT HEATED OXYGEN SENSOR (HO2S1) SLOW
RESPONSE
Circuit Description
The Engine Control Module (ECM) continuously monitors
the Front Heated Oxygen Sensor (HO2S1) activity for 100
seconds. During the monitor period, the ECM counts the
number of times that the HO2S1 switches from rich to lean
and from lean to rich and adds the amount of time it took
to complete all switches. With this information, an average
time for all switches can be determined. If the average time
to switch is too out of specification, a DTC P0133 will set.
If the HO2S1 pigtail wiring, connector, or terminal is dam-
aged, the entire HO2S1 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 a
clean air reference provided to it. This clean air reference
is obtained by way of the HO2S1 wire(s). Any attempt to
repair the wires, connector, or terminals could result in the
obstruction of the air reference and degrade HO2S1 per-
formance.
Conditions for Setting the DTCS HO2S1 average transition time between 0.3–0.6
volts, lean to rich is greater than 156 millisec-
onds(A/T) or rich to lean is greater than 140 milli-
seconds (M/T).
S Closed loop stoichiometry.
S Engine Coolant Temperature (ECT) is greater than
70°C (158°F).
S System voltage is greater than 10 volts.
S Engine run time is greater than 60 seconds.
S Purge Duty Cycle (DC) is less than 20%.
S The rpm is between 1600 and 4300.
S Airflow is between 9 and 40 g/sec.
S DTCs P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0131, P0132, P0134, P0135,
P1167, P0171, P1171, P0172, P0201, P0202,
P0203, P0204, P0300, P0336, P0337, P0351,
P0352, P0402, P0404, P0405, P0406, P0506,
P0507, P1404, and P0443 are not set.
S 2 second delay after conditions are met.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive ignition cycle with a fail.

1F – 468IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0401
EXHAUST GAS RECIRCULATION INSUFFICIENT FLOW
Circuit Description
An Exhaust Gas Recirculation (EGR) system is used to
lower Nitrogen Oxide (NOx) emission levels caused by
high combustion temperatures. It accomplishes this by
feeding small amounts of exhaust gases back into the
combustion chamber. When the air/fuel mixture is diluted
with the exhaust gases, combustion temperatures are re-
duced
A linear EGR valve is used on this system. The linear EGR
valve is designed to accurately supply exhaust gases to
the engine without the use of intake manifold vacuum. The
valve controls exhaust flow going into the intake manifold
from the exhaust manifold through an orifice with an En-
gine Control Module (ECM) controlled pintle. The ECM
controls the pintle position using inputs from the Throttle
Position (TP) and Manifold Absolute Pressure (MAP) sen-
sors. The ECM then commands the EGR valve to operate
when necessary by controlling an ignition signal through
the ECM. This can be monitored on a scan tool as the De-
sired EGR Position.
The ECM monitors the results of its command through a
feedback signal. By sending a 5 volt reference and a
ground to the EGR valve, a voltage signal representing the
EGR valve pintle position is sent to the ECM. This feed-
back signal can also be monitored on a scan tool and is the
actual position of the EGR pintle. The Actual EGR Position
should always be near the commanded or Desired EGR
Position.
This diagnostic will determine if there is a reduction in EGR
flow.
Conditions for Setting the DTC
S DTCs P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0201, P0202, P0203, P0204,
P0351, P0352, P0402, P0404, P1404, P0405,
P0406 and P0502 are not set.
S Test in Decel Fuel Cutoff (DFCO) mode.
S Barometric Pressure (BARO) is greater than 72
kPa (10.4 psi).
S Vehicle speed is greater than 18 km/h (11.2
mph).
S A/C clutch/transmission clutch are unchanged.
S Rpm is between 1400 and 3000 for manual
transaxle.
S Rpm is between 1300 and 2900 for automatic
transaxle.
S Compensated MAP is with 10.3 to 32 kpa (1.5 to
4.6 psi) range.
S Start test
S Throttle position (TP) sensor is less then 1%.
S EGR is less than 1%.
S Change in MAP is less than 1.0 kpa (0.15 psi)Note : Test will be aborted when:
S Change in vehicle speed is greater than 5km/h (3.1
mph).
S Rpm is increased more than 75.
S EGR opened less than 90% commanded position.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will not illumi-
nate.
S The ECM will store conditions which were present
when the DTC set as Failure Records data only.
This information will not be stored in the Freeze
Frame data.
S A history Diagnostic Trouble Code (DTC) is stored.
S EGR is disabled.
Conditions for Clearing the MIL/DTC
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
The EGR Decel Filter value can be a great aid in determin-
ing if a problem exists and to verify repairs. The EGR De-
cel Filter is an average of the difference in the expected
MAP change and the actual MAP change caused by open-
ing the EGR valve during a deceleration, and is used to de-
termine when the MIL is illuminated. By driving the vehicle
up to approximately 97 km/h (60 mph) and decelerating to
32 km/h (20 mph), it can be determined if the EGR system
is OK, partially restricted, or fully restricted.
A more negative number (less than –3) indicates that the
system is working normally, whereas a positive number in-
dicates that the system is being restricted and that the ex-
pected amount of EGR flow is was not seen. A number
that falls between negative 3 and positive 2 indicates that
the system is partially restricted but not restricted enough
to cause an emissions impact.
The EGR Decel Filter value should always be at –3 or low-
er. If the EGR Decel Filter number becomes more positive
(towards 0 or more), then the EGR system is becoming re-
stricted. Look for possible damage to the EGR pipe or for
a restriction caused by carbon deposits in the EGR pas-
sages or on the EGR valve.
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

1F – 484IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0420
CATALYST OXYGEN SENSOR LOW EFFICIENCY
Circuit Description
In order to control exhaust emissions of Hydrocarbons
(HC), Carbon Monoxide (CO) and Nitrogen Oxide (NOx),
a Three–Way Catalytic Converter (TWC) is used. The cat-
alyst within the converter promotes a chemical reaction
which oxidizes the HC and CO present in the exhaust gas,
converting them into harmless water vapor and carbon
dioxide, it also reduces NOx, converting it into nitrogen.
The catalytic converter also has the ability to store oxygen.
The Engine Control Module (ECM) has the capability to
monitor this process using a Heated
Rear Heated Oxygen Sensor (HO2S2) located in the ex-
haust stream past the TWC. The HO2S2 produces an out-
put signal which indicates the oxygen storage capacity of
the catalyst; this in turn indicates the catalyst’s ability to
convert exhaust emissions effectively. The ECM monitors
the catalyst efficiency by first allowing the catalyst to heat
up, waiting for a stabilization period while the engine is id-
ling, and then adding and removing fuel while monitoring
the reaction of the HO2S2. When the catalyst is function-
ing properly, the HO2S2 response to the extra fuel is slow
compared to the Front Heated Oxygen Sensor (HO2S1).
When the HO2S2 response is close to that of the HO2S1,
the Oxygen storage capability or efficiency of the catalyst
is considered to be bad, and the Malfunction Indicator
Lamp (MIL) will illuminate.
Conditions for Setting the DTC
S Oxygen storage capacity index time is less than 0.3
seconds.
S Before idle test, the vehicle needs to be driven for
at least:
S 15 seconds at airflow is greater than 9.2 g/sec.
for manual transaxle.
S 11 seconds at airflow is greater than 12 g/sec
for automatic transaxle.
S Oxygen Sensor Capacity test condition:
S Closed loop stoichiometry.
S Purge concentration learned.
S Engine is running more than 330 seconds.
S Airflow is between 2.5 and 7.25 g/sec.
S Throttle Position (TP) sensor is less than 1.5%.
S Intake Air Temperature (IAT) is between –7°C
(19.4°F) and 105°C (221°F).
S Barometric pressure (BARO) is greater than 72 kPa
(10.4 psi).
S Catalyst temperature is between 500°C (932°F)
and 850°C (1562°F) for automatic transaxle.
S Catalyst temperature is between 450°C (842°F)
and 850°C (1562°F) for automatic transaxle.
S Closed Loop integrator change is less than 0.03.
S Idle time is less than 1 minute.
S Vehicle speed is less than 3 km/h (1.9 mph).S Block Learn Mode is learned.
S Above condition is stabilized for 5 seconds.
Note : Test is aborted for this idle if:
S Change in engine speed is greater than 80 rpm.
S A/C status changed.
S Cooling fan status changed.
S Insufficient air/fuel shift.
S DTC(s) P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0131, P0132, P0133, P1133,
P0134, P0135, P0137, P0138, P0140, P0141,
P1167, P1171, P0171, P0172, P0201, P0202,
P0203, P0204, P0300, P0336, P0337, P0341,
P0342, P0351, P0352, P0402, P0404, P1404,
P0405, P0406, P0443, P0502, P0506, P0507, and
P0562 are not set.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
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
The catalyst test may abort due to a change in the engine
load. Do not change the engine load (i.e. A/C, coolant fan,
heater motor) while a catalyst test is in progress.
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.
Any circuitry, that is suspected as causing the intermittent
complaint, 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
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Table.

1F – 498IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0502
VEHICLE SPEED SENSOR NO SIGNAL (ENGINE SIDE)
Circuit Description
Vehicle speed information is provided to the Engine Con-
trol Module (ECM) by the Vehicle Speed Sensor (VSS).
The VSS is a permanent magnet generator that is
mounted in the transaxle and produces a pulsing voltage
whenever vehicle speed is over 3 mph (5 km/h). The Alter-
nating Current (AC) voltage level and the number of
pulses increases with vehicle speed. The ECM converts
the pulsing voltage into mph (km/h) and then supplies the
necessary signal to the instrument panel for speedometer/
odometer operation and to the cruise control module and
multi–function alarm module operation. This Diagnostic
Trouble Code (DTC) will detect if vehicle speed is reason-
able according to engine rpm and load.
Conditions for Setting the DTC
S Vehicle speed is less than 5 km/h (3.1 mph) for
Power and Decel test.
S Engine is running.
S Engine Coolant Temperature (ECT) is greater than
60 °C (140 °F).
S Ignition voltage is between 11–16 volts.
S Power Test
S The rpm is between 1200 and 4000.S Throttle Position (TP) sensor is between 25%
and 60%.
S MAP is greater than 60 kPa (8.7 psi).
S Deceleration Test
S Generator compensated Manifold Absolute
Pressure (MAP) is less than 30 kPa (4.4 psi)
S Change in rpm per cycle is less than 50 rpm/
cycle.
S Throttle Position (TP) sensor is less than 0.8%.
S The rpm is between 1800 and 6000.
S DTC(s) P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0201, P0202, P0203, P0204,
P0300, P0351, P0352, P0402, P0404, P1404,
P0405, and P0406 are not set.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC

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