2004 DAEWOO LACETTI engine controls

ENGINE CONTROLS 1F – 631
DAEWOO V–121 BL4
S Barometric Pressure (BARO)
S Intake Air Temperature (IAT)
S Throttle Position (TP)
S High canister purge
S Fuel trim
S A/C on
Trip
Technically, a trip is a key–on run key–off cycle in which all
the enable criteria for a given diagnostic are met, allowing
the diagnostic to run. Unfortunately, this concept is not
quite that simple. A trip is official when all the enable crite-
ria for a given diagnostic are met. But because the enable
criteria vary from one diagnostic to another, the definition
of trip varies as well. Some diagnostics are run when the
vehicle is at operating temperature, some when the ve-
hicle first starts up; some require that the vehicle be cruis-
ing at a steady highway speed, some run only when the
vehicle is at idle; some diagnostics function with the
Torque Converter Clutch (TCC) disabled. Some run only
immediately following a cold engine startup.
A trip then, is defined as a key–on run key–off cycle in
which the vehicle was operated in such a way as to satisfy
the enables criteria for a given diagnostic, and this diag-
nostic will consider this cycle to be one trip. However,
another diagnostic with a different set of enable criteria
(which were not met) during this driving event, would not
consider it a trip. No trip will occur for that particular diag-
nostic until the vehicle is driven in such a way as to meet
all the enable criteria
Diagnostic Information
The diagnostic charts and functional checks are designed
to locate a faulty circuit or component through a process
of logical decisions. The charts are prepared with the re-
quirement that the vehicle functioned correctly at the time
of assembly and that there are not multiple faults present.
There is a continuous self–diagnosis on certain control
functions. This diagnostic capability is complimented by
the diagnostic procedures contained in this manual. The
language of communicating the source of the malfunction
is a system of diagnostic trouble codes. When a malfunc-
tion is detected by the control module, a diagnostic trouble
code is set and the Malfunction Indicator Lamp (MIL) is illu-
minated.
Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) is required by On–
Board Diagnostics (EOBD) that it illuminates under a strict
set of guide lines.
Basically, the MIL is turned on when the engine control
module (ECM) detects a DTC that will impact the vehicle
emissions.The MIL is under the control of the Diagnostic Executive.
The MIL will be turned on if an emissions–related diagnos-
tic test indicates a malfunction has occurred. It will stay on
until the system or component passes the same test, for
three consecutive trips, with no emissions related faults.
Extinguishing the MIL
When the MIL is on, the Diagnostic Executive will turn off
the MIL after three consecutive trips that a ”test passed”
has been reported for the diagnostic test that originally
caused the MIL to illuminate. Although the MIL has been
turned off, the DTC will remain in the ECM memory (both
Freeze Frame and Failure Records) until forty (40) warm–
up cycles after no faults have been completed.
If the MIL was set by either a fuel trim or misfire–related
DTC, additional requirements must be met. In addition to
the requirements stated in the previous paragraph, these
requirements are as follows:
S The diagnostic tests that are passed must occur
with 375 rpm of the rpm data stored at the time the
last test failed.
S Plus or minus ten percent of the engine load that
was stored at the time the last test failed. Similar
engine temperature conditions (warmed up or
warming up) as those stored at the time the last
test failed.
Meeting these requirements ensures that the fault which
turned on the MIL has been corrected.
The MIL is on the instrument panel and has the following
functions:
S It informs the driver that a fault that affects vehicle
emission levels has occurred and that the vehicle
should be taken for service as soon as possible.
S As a system check, the MIL will come on with the
key ON and the engine not running. When the en-
gine is started, the MIL will turn OFF.
S When the MIL remains ON while the engine is run-
ning, or when a malfunction is suspected due to a
driveability or emissions problem, an EOBD System
Check must be performed. The procedures for
these checks are given in EOBD System Check.
These checks will expose faults which may not be
detected if other diagnostics are performed first.
Data Link Connector (DLC)
The provision for communicating with the control module
is the Data Link Connector (DLC). The DLC is used to con-
nect to a scan tool. Some common uses of the scan tool
are listed below:
S Identifying stored DTCs.
S Clearing DTCs.
S Performing output control tests.
S Reading serial data.

1F – 632IENGINE CONTROLS
DAEWOO V–121 BL4
READING DIAGNOSTIC TROUBLE
CODES
The procedure for reading diagnostic trouble code(s) is to
use a diagnostic scan tool. When reading Diagnostic
Trouble Codes (DTCs), follow the instructions supplied by
tool manufacturer.
DTC Modes
On On–Board Diagnostic (EOBD) passenger cars there
are five options available in the scan tool DTC mode to dis-
play the enhanced information available. A description of
the new modes, DTC Info and Specific DTC, follows. After
selecting DTC, the following menu appears:
S DTC Info.
S Specific DTC.
S Freeze Frame.
S Fail Records (not all applications).
S Clear Info.
The following is a brief description of each of the sub me-
nus in DTC Info and Specific DTC. The order in which they
appear here is alphabetical and not necessarily the way
they will appear on the scan tool.
DTC Information Mode
Use the DTC info mode to search for a specific type of
stored DTC information. There are seven choices. The
service manual may instruct the technician to test for
DTCs in a certain manner. Always follow published service
procedures.
To get a complete description of any status, press the ”En-
ter” key before pressing the desired F–key. For example,
pressing ”Enter” then an F–key will display a definition of
the abbreviated scan tool status.
DTC Status
This selection will display any DTCs that have not run dur-
ing the current ignition cycle or have reported a test failure
during this ignition up to a maximum of 33 DTCs. DTC
tests which run and pass will cause that DTC number to
be removed from the scan tool screen.
Fail This Ign. (Fail This Ignition)
This selection will display all DTCs that have failed during
the present ignition cycle.
History
This selection will display only DTCs that are stored in the
ECM’s history memory. It will not display type CNL DTCs
that have not requested the Malfunction Indicator Lamp
(MIL). It will display all type A, B and E DTCs that have re-
quested the MIL and have failed within the last 40 warm–
up cycles. In addition, it will display all type C and type D
DTCs that have failed within the last 40 warm–up cycles.
Last Test Fail
This selection will display only DTCs that failed the last
time the test ran. The last test may have run during a pre-
vious ignition cycle if a type A or type B DTC is displayed.
For type C and type D DTCs, the last failure must have oc-
curred during the current ignition cycle to appear as Last
Test Fail.
MIL Request
This selection will display only DTCs that are requesting
the MIL. Type C and type D DTCs cannot be displayed us-
ing this option. This selection will report type B DTCs only
after the MIL has been requested.
Not Run SCC (Not Run Since Code Clear)
This option will display up to 33 DTCs that have not run
since the DTCs were last cleared. Since any displayed
DTCs have not run, their condition (passing or failing) is
unknown.
Test Fail SCC (Test Failed Since Code
Clear)
This selection will display all active and history DTCs that
have reported a test failure since the last time DTCs were
cleared. DTCs that last failed more than 40 warm–up
cycles before this option is selected will not be displayed.
Specific DTC Mode
This mode is used to check the status of individual diag-
nostic tests by DTC number. This selection can be ac-
cessed if a DTC has passed, failed or both. Many EOBD
DTC mode descriptions are possible because of the ex-
tensive amount of information that the diagnostic execu-
tive monitors regarding each test. Some of the many pos-
sible descriptions follow with a brief explanation.
The ”F2” key is used, in this mode, to display a description
of the DTC. The ”Yes” and ”No” keys may also be used to
display more DTC status information. This selection will
only allow entry of DTC numbers that are supported by the
vehicle being tested. If an attempt is made to enter DTC
numbers for tests which the diagnostic executive does not
recognize, the requested information will not be displayed
correctly and the scan tool may display an error message.
The same applies to using the DTC trigger option in the
Snapshot mode. If an invalid DTC is entered, the scan tool
will not trigger.
Failed Last Test
This message display indicates that the last diagnostic
test failed for the selected DTC. For type A and type B
DTCs, this message will be displayed during subsequent
ignition cycles until the test passes or DTCs are cleared.
For type C and type D DTCs, this message will clear when
the ignition is cycled.
Failed Since Clear
This message display indicates that the DTC has failed at
least once within the last 40 warm–up cycles since the last
time DTCs were cleared.

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.

1F – 634IENGINE CONTROLS
DAEWOO V–121 BL4
A rough road sensor, or G sensor, works together with the
misfire detection system. The G sensor produces a volt-
age that varies along with the intensity of road vibrations.
When the ECM detects a rough road, the misfire detection
system is temporarily disabled.
Misfire Counters
Whenever a cylinder misfires, the misfire diagnostic
counts the misfire and notes the crankshaft position at the
time the misfire occurred. These ”misfire counters” are ba-
sically a file on each engine cylinder. A current and a histo-
ry misfire counter are maintained for each cylinder. The
misfire current counters (Misfire Cur #1–4) indicate the
number of firing events out of the last 200 cylinder firing
events which were misfires. The misfire current counter
will display real time data without a misfire Diagnostic
Trouble Code (DTC) stored. The misfire history counters
(Misfire Hist #1–4) indicate the total number of cylinder fir-
ing events which were misfires. The misfire history count-
ers will display 0 until the misfire iagnostic has failed and
a DTC P0300 is set. Once the misfire DTC P0300 is set,
the misfire history counters will be updated every 200 cyl-
inder firing events. A misfire counter is maintained for each
cylinder.
If the misfire diagnostic reports a failure, the diagnostic
executive reviews all of the misfire counters before report-
ing a DTC. This way, the diagnostic executive reports the
most current information.
When crankshaft rotation is erratic, a misfire condition will
be detected. Because of this erratic condition, the data
that is collected by the diagnostic can sometimes incor-
rectly identify which cylinder is misfiring.
Use diagnostic equipment to monitor misfire counter data
on On–Board Diagnostic (EOBD) compliant vehicles.
Knowing which specific cylinder(s) misfired can lead to the
root cause, even when dealing with amultiple cylinder mis-
fire. Using the information in the misfire counters, identify
which cylinders are misfiring. If the counters indicate cylin-
ders numbers 1 and 4 misfired, look for a circuit or compo-
nent common to both cylinders number 1 and 4.
The misfire diagnostic may indicate a fault due to a tempo-
rary fault not necessarily caused by a vehicle emission
system malfunction. Examples include the following
items:
S Contaminated fuel.S Low fuel.
S Fuel–fouled spark plugs.
S Basic engine fault.
Fuel Trim System Monitor Diagnostic
Operation
This system monitors the averages of short–term and
long–term fuel trim values. If these fuel trim values stay at
their limits for a calibrated period of time, a malfunction is
indicated. The fuel trim diagnostic compares the averages
of short–term fuel trim values and long–term fuel trim val-
ues to rich and lean thresholds. If either value is within the
thresholds, a pass is recorded. If both values are outside
their thresholds, a rich or lean DTC will be recorded.
The fuel trim system diagnostic also conducts an intrusive
test. This test determines if a rich condition is being
caused by excessive fuel vapor from the Evaporative
(EVAP) Emission canister. In order to meet EOBD require-
ments, the control module uses weighted fuel trim cells to
determine the need to set a fuel trim DTC. A fuel trim DTC
can only be set if fuel trim counts in the weighted fuel trim
cells exceed specifications. This means that the vehicle
could have a fuel trim problem which is causing a problem
under certain conditions (i.e., engine idle high due to a
small vacuum leak or rough idle due to a large vacuum
leak) while it operates fine at other times. No fuel trim DTC
would set (although an engine idle speed DTC or HO2S2
DTC may set). Use a scan tool to observe fuel trim counts
while the problem is occurring.
A fuel trim DTC may be triggered by a number of vehicle
faults. Make use of all information available (other DTCs
stored, rich or lean condition, etc.) when diagnosing a fuel
trim fault.
Fuel Trim Cell Diagnostic Weights
No fuel trim DTC will set regardless of the fuel trim counts
in cell 0 unless the fuel trim counts in the weighted cells are
also outside specifications. This means that the vehicle
could have a fuel trim problem which is causing a problem
under certain conditions (i.e. engine idle high due to a
small vacuum leak or rough due to a large vacuum leak)
while it operates fine at other times. No fuel trim DTC
would set (although an engine idle speed DTC or HO2S2
DTC may set). Use a scan tool to observe fuel trim counts
while the problem is occurring.

ANTILOCK BRAKE SYSTEM 4F – 71
DAEWOO V–121 BL4
TIRES AND ABS/EBD
Replacement Tires
Tire size is important for proper performance of the ABS
system. Replacement tires should be the same size, load
range, and construction as the original tires. Replace tires
in axle sets and only with tires of the same tire perfor-
mance criteria (TPC) specification number. Use of any
other size or type may seriously affect the ABS operation.
TIRES AND ABS/EBD
Notice : There is no serviceable or removable EEPROM.
The EBCM must be replaced as an assembly.
The EBCM is attached to the hydraulic unit in the engine
compartment. The controlling element of ABS 5.3 is a mi-
croprocessor–based EBCM. Inputs to the system include
the four wheel speed sensors, the stoplamp switch, the
ignition switch, and the unswitched battery voltage. There
is an output to a bi–directional serial data link, located in
pin K of Data Link Connector (DLC) for service diagnostic
tools and assembly plant testing.
The EBCM monitors the speed of each wheel. If any wheel
begins to approach lockup and the brake switch is closed
(brake pedal depressed), the EBCM controls the sole-
noids to reduce brake pressure to the wheel approaching
lockup. Once the wheel regains traction, brake pressure
is increased until the wheel again begins to approach lock-
up. This cycle repeats until either the vehicle comes to a
stop, the brake pedal is released, or no wheels approach
lockup.
Additionally, the EBCM monitors itself, each input (except
the serial data link), and each output for proper operation.
If it detects any system malfunction, the EBCM will store
a DTC in nonvolatile memory (EEPROM) (DTCs will not
disappear if the battery is disconnected). Refer to ”Self
Diagnostics” in this section for more detailed information.
FRONT WHEEL SPEED SENSOR
The front wheel speed sensors are of a variable reluctance
type. Each sensor is attached to the steering knuckle,
close to a toothed ring. The result, as teeth pass by the
sensor, is an AC voltage with a frequency proportional to
the speed of the wheel. The magnitude of the voltage and
frequency increase with increasing speed. The sensor is
not repairable, nor is the air gap adjustable.
FRONT WHEEL SPEED SENSOR
RINGS
The toothed ring mentioned above is pressed onto the
wheel–side (outer) constant velocity joint. Each ring con-
tains 47 equally spaced teeth. Exercise care during ser-
vice procedures to avoid prying or contacting this ring. Ex-cessive contact may cause damage to one or more teeth.
If the ring is damaged, the wheel–side constant velocity
joint must be replaced.
REAR WHEEL SPEED SENSOR AND
RINGS
The rear wheel speed sensors operate in the same man-
ner as the front wheel speed sensors. They incorporate a
length of flexible harness with the connector attached to
the end of the harness. The rear wheel speed rings are in-
corporated into the hub assemblies and cannot be re-
placed separately, but require replacement of the rear
hub/bearing assembly.
VALUE RELAY AND PUMP MOTOR
RELAY
The valve relay and the motor pump relay are located in-
side the electronic brake control module (EBCM) and are
not replaceable. If one should fail, replace the EBCM.
WIRING HARNESS
The wiring harness is the mechanism by which the elec-
tronic brake control module (EBCM) is electrically con-
nected to power and to ground, to the wheel speed sen-
sors, the fuses, the switches, the indicators, and the serial
communications port. The components, considered part
of the wiring harness, are the wires that provide electrical
interconnection, and connectors (terminals, pins, con-
tacts, or lugs) that provide an electrical/mechanical inter-
face from the wire to a system component.
INDICATORS
The electronic brake control module (EBCM) continuously
monitors itself and the other ABS components. If the
EBCM detects a problem with the system, the amber ABS
indicator will light continuously to alert the driver to the
problem. An illuminated ABS indicator indicates that the
ABS system has detected a problem that affects the op-
eration of ABS. No antilock braking will be available. Nor-
mal, non–antilock brake performance will remain. In order
to regain ABS braking ability, the ABS must be serviced.
The red BRAKE indicator will be illuminated when the sys-
tem detects a low brake fluid level in the master cylinder
or when the parking brake switch is closed (the parking
brake is engaged) or EBD system is diabled.
WARNING : EBD INDICATOR LAMP WIRING IS CON-
NECTED TO THE PARKING BRAKE LAMP. IF THE
PARKING BRAKE LAMP IS TURNED ON WHEN YOU
DRIVING, CHECKING ON WHETHER THE PARKING
BRAKE LEVER IS ENAGED OR THE BRAKE FLUID
LEVEL IS LOW. IF THE SYSTEM HAS NO PROBLEM,
THE EBD SYSTEM IS WORKING IMPROPERLY. THE
EBD SYSTEM MUST BE SERVICED.

5A1 – 18IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
Park/Neutral
In Park or Neutral with the engine running there is no drive
to the planetary gear set. Line pressure (from the oil pump)
is supplied to the valve body. Only clutch B is supplied and
the torque converter is released.
Control
Line Pressure Control Valve
The line pressure control valve sets the general pressure
level in the valve body. When gearshifts are not taking
place, the line pressure varies between two levels, de-
pending on the turbine torque. Line pressure increase lin-
early by time. But it has a limit point. When pressure reach-
es that point, excess oil pressure drains back into the oil
sump.
Reduction Valve
The reduction valve reduces the line pressure with which
the downstream solenoid valves and pressure control so-
lenoid valves (EDS) are supplied. This makes it possible
to use smaller solenoid valves.
The line pressure comes from the oil pump and flows to the
reduction valve. The inlet port to the reduction valve will be
blocked and line pressure will be maintained at the ap-
propriate level.
Solenoid Valve 1, 2
Solenoid Valve 1 controls the line pressure (high and low)
to the clutch valves. Solenoid Valve 1 is either ON or OFF.
When the solenoid is turned ON the line pressure will be
low [87~116psi (6~8bar)].When the solenoid is turned
OFF the line pressure will be high [232~261psi
(16~18bar)].
Solenoid 2 controls the fluid flow to clutch valve E or the
TCC clutch valve. When solenoid 2 is ON fluid is directed
to the TCC pressure valve and if the solenoid is switched
OFF fluid will flow to the inlet at clutch valve E.The TCM monitors numerous inputs to determine the ap-
propriate solenoid state combination and transaxle gear
for the vehicle operating conditions.
In Park and Neutral solenoid valve 1 is ON. So line pres-
sure flows to the safety valve and the line pressure control
valve via the solenoid valve.
Clutch B Engaged
In Park and Neutral solenoid valves 1 and 2 are both ON.
Pressure control solenoids (EDS) 4 and 6 are also turned
ON.
When EDS 6 is ON, the fluid supplied from the reduction
valve flows to the safety valve, clutch valve B and holding
valve B. The oil that is supplied to the inlet port of the clutch
valve presses on the valve spool. Line pressure then flows
to the holding valve and check ball, engaging clutch B.
Lock–up Clutch (TCC)
Solenoid 2 is turned ON and the line pressure control
valves spool will be depressed. Fluid will now flow through
the torque converter pressure valve.
As a result, the oil pressure behind the converter lock–up
clutch piston and in the turbine zone is equal. The direction
of flow is through the turbine shaft and through the space
behind the piston, to the turbine chamber.
Lubrication/Cooling.
The lubricating valve ensures that the converter is sup-
plied with cooling oil first if the pump rate is low. The lubri-
cating pressure valve in addition guarantees that the nec-
essary amount of cooling and lubricating oil is available via
the bypass duct.
The fluid, which is supplied from the torque converter,
flows to the cooler via the lubrication valve.

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 47
DAEWOO V–121 BL4
Repairing the Fluid Leak
Once the leak point is found the source of the leak must
be determined. The following list describes the potential
causes for the leak:
S Fasteners are not torqued to specification.
S Fastener threads and fastener holes are dirty or
corroded.
S Gaskets, seals or sleeves are misarranged, dam-
aged or worn.
S Damaged, warped or scratched seal bore or gasket
surface.
S Loose or worn bearing causing excess seal or
sleeve wears.
S Case or component porosity.
S Fluid level is too high.
S Plugged vent or damaged vent tube.
S Water or coolant in fluid.
S Fluid drain back holes plugged.
ELECTRICAL/GARAGE SHIFT TEST
This preliminary test should be performed before a hoist
or road test to make sure electronic control inputs is con-
nected and operating. If the inputs are not checked before
operating the transaxle, a simple electrical condition could
be misdiagnosed as a major transaxle condition.
A scan tool provides valuable information and must be
used on the automatic transaxle for accurate diagnosis.
1. Move gear selector to P (Park) and set the parking
brake.
2. Connect scan tool to Data Link Connector (DLC)
terminal.
3. Start engine.
4. Turn the scan tool ON.
5. Verify that the appropriate signals are present.
These signals may include:
S ENGINE SPEED
S VEHICLE SPEED
S THROTTLE POSITION
S TRANSAXLE GEAR STATE
S GEAR SHIFT LEVER POSITION
S TRANSAXLE FLUID TEMPERATURE
S CLOSED THROTTLE POSITION LEARN
S OPEN THROTTLE POSITION LEARNT
S CLOSED ACCEL. PEDAL POSITION LEARNT
S OPEN ACCEL. PEDAL POSITION LEARNT
S A/C COMPRESSOR STATUS
S MODE SWITCH
S THROTTLE POSITION VOLTAGE
S GEAR SHIFT LEVER POSITION VOLTAGE
S TRANS. FLUID TEMPERATURE VOLTAGE
S A/C SWITCH
S MODE SWITCH VOLTAGE
S BATTERY VOLTAGE
6. Monitor the A/C COMPRESSOR STATUS signal
while pushing the A/C switch.S The A/C COMPRESSOR STATUS should come
ON when the A/C switch is pressed, and turns
OFF when the A/C switch is repushed.
7. Monitor the GEAR SHIFT LEVER POSITION signal
and move the gear shift control lever through all the
ranges.
S Verify that the GEAR SHIFT LEVER POSITION
value matches the gear range indicated on the
instrument panel or console.
S Gear selections should be immediate and not
harsh.
8. Move gear shift control lever to neutral and monitor
the THROTTLE POSITION signal while increasing
and decreasing engine speed with the accelerator
pedal.
S THROTTLE POSITION should increase with
engine speed.
ROAD TEST PROCEDURE
S Perform the road test using a scan tool.
S This test should be performed when traffic and road
conditions permit.
S Observe all traffic regulations.
The TCM calculates upshift points based primarily on two
inputs : throttle angle and vehicle speed. When the TCM
wants a shift to occur, an electrical signal is sent to the shift
solenoids which in turn moves the valves to perform the
upshift.
The shift speed charts reference throttle angle instead of
”min throttle” or ”wot” to make shift speed measurement
more uniform and accurate. A scan tool should be used to
monitor throttle angle. Some scan tools have been pro-
grammed to record shift point information. Check the
introduction manual to see if this test is available.
Upshift Procedure
With gear selector in drive(D)
1. Look at the shift speed chart contained in this sec-
tion and choose a percent throttle angle of 10 or
25%.
2. Set up the scan tool to monitor throttle angle and
vehicle speed.
3. Accelerate to the chosen throttle angle and hold the
throttle steady.
4. As the transaxle upshifts, note the shift speed and
commanded gear changes for :
S Second gear.
S Third gear.
S Fourth gear.
Important : Shift speeds may vary due to slight hydraulic
delays responding to electronic controls. A change from
the original equipment tire size affects shift speeds.
Note when TCC applies. This should occur in fourth gear.
If the apply is not noticed by an rpm drop, refer to the
”Lock–up Clutch Diagnosis” information contained in this
section.

5A1 – 58IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
Symptom ActionPossible Cause
NoiseThe Engine’s Torsional Vibrations are
Being Transmitted to the Drive ShaftsS At low speeds in fourth gear, vibration can
arise (driving at too low an engine speed)
S Noise is functionally unavoidable; due to toler-
ances. Convince the customer.
NoiseTorque Reaction Strut LooseS Check mounting and repair if necessary.
Shift quality
Notice :
– The assessment of shaft quality is, to a large ex-
tent, an individual, subjective matter. Take careful
note of how the customer describes the complaint
and of the manner in which he or she handles the
vehicle and the controls.
– A sudden deterioration of shift quality may also
be caused by the transaxle selecting an emergency
or substitute program
Test Steps :– Carry out the general checks described in the
automatic transaxle diagnostic information.
– Perform a test drive to answer the following ques-
tions.
In which driving situations does the shift quality
complaint arise?
To which shifts does the complaint apply?
Is the complaint reproducible within a short period,
or has it only occurred sporadically or on a single
occasion?
– Check the oil level and oil quality
– Interrogate the fault memory and read out mea-
surement block data.
Symptom
Possible CauseAction
Shift QualityRapid Pressure Build–up in the ClutchS Operating error (position selected several times
in quick succession).
Jerk When Parking Lock Is ReleasedS Refer to ”Noise” in this section.
Incorrect Electronic Transaxle Control
moduleS Check the data status for transaxle control
module ; refer to ”TCM” in this section.
Emergency/Substitute Program Has
Been ActivatedS For checking and remedial action, refer to
”Emergency/Substitute program” in this sec-
tion.
Accelerator Pedal in Indefinite Position
Between Full Throttle and Kick DownS Persuade customer to choose clearly between
kick down and full throttle
S Check setting according go engine repair in-
struction ; adjust if necessary.
Control Overlap Between to Clutches
During ShiftS Production status
S Convince the customer
Temperature Sensor
(Not Fault Memory)S Check function according to ”Emergency/Sub-
stitute program” in this section.
Kick Down Setting IncorrectS Check
A) Floor mat is obstructing accelerator pedal
B) The kick down setting as described in the
Engine Section.
Malfunction
Notice :
The faults dealt with here concern transaxle functions
such as ”traction” (forwards and reverse) and all type of
shifts. Entries will not always be made in the fault memory.Test Steps :
Perform the general checks according to the automatic
transaxle diagnostic procedure.
– Test drive
– Check oil level and quality
– Interrogate fault memory