2004 DAEWOO LACETTI Throttle body

1F – 626IENGINE CONTROLS
DAEWOO V–121 BL4
EXHAUST GAS RECIRCULATION
VA LV E
The Exhaust Gas Recirculation (EGR) system is used on
engines equipped with an automatic transaxle to lower
NOx (oxides of nitrogen) emission levels caused by high
combustion temperature. The EGR valve is controlled by
the engine control module (ECM). The EGR valve feeds
small amounts of exhaust gas into the intake manifold to
decrease combustion temperature. The amount of ex-
haust gas recirculated is controlled by variations in vacu-
um and exhaust back pressure. If too much exhaust gas
enters, combustion will not take place. For this reason,
very little exhaust gas is allowed to pass through the valve,
especially at idle.
The EGR valve is usually open under the following condi-
tions:
S Warm engine operation.
S Above idle speed.
Results of Incorrect Operation
Too much EGR flow tends to weaken combustion, causing
the engine to run roughly or to stop. With too much EGR
flow at idle, cruise, or cold operation, any of the following
conditions may occur:
S The engine stops after a cold start.
S The engine stops at idle after deceleration.
S The vehicle surges during cruise.
S Rough idle.
If the EGR valve stays open all the time, the engine may
not idle. Too little or no EGR flow allows combustion tem-
peratures to get too high during acceleration and load con-
ditions. This could cause the following conditions:
S Spark knock (detonation)
S Engine overheating
S Emission test failure
INTAKE AIR TEMPERATURE
SENSOR
The Intake Air Temperature (IAT) sensor is a thermistor,
a resistor which changes value based on the temperature
of the air entering the engine. Low temperature produces
a high resistance (4,500 ohms at –40°F [–40°C]), while
high temperature causes a low resistance (70 ohms at
266°F [130°C]).
The engine control module (ECM) provides 5 volts to the
IAT sensor through a resistor in the ECM and measures
the change in voltage to determine the IAT. The voltage will
be high when the manifold air is cold and low when the air
is hot. The ECM knows the intake IAT by measuring the
voltage.
The IAT sensor is also used to control spark timing when
the manifold air is cold.
A failure in the IAT sensor circuit sets a diagnostic trouble
code P0112 or P0113.
IDLE AIR CONTROL VALVE
Notice : Do not attempt to remove the protective cap to
readjust the stop screw. Misadjustment may result in dam-
age to the Idle Air Control (IAC) valve or to the throttle
body.
The IAC valve is mounted on the throttle body where it
controls the engine idle speed under the command of the
engine control module (ECM). The ECM sends voltage
pulses to the IAC valve motor windings, causing the IAC
valve pintle to move in or out a given distance (a step or
count) for each pulse. The pintle movement controls the
airflow around the throttle valves which, in turn, control the
engine idle speed.
The desired idle speeds for all engine operating conditions
are programmed into the calibration of the ECM. These
programmed engine speeds are based on the coolant
temperature, the park/neutral position switch status, the
vehicle speed, the battery voltage, and the A/C system
pressure (if equipped).
The ECM ”learns” the proper IAC valve positions to
achieve warm, stabilized idle speeds (rpm) desired for the
various conditions (park/neutral or drive, A/C on or off, if
equipped). This information is stored in ECM ”keep alive”
memories. Information is retained after the ignition is
turned OFF. All other IAC valve positioning is calculated
based on these memory values. As a result, engine varia-
tions due to wear and variations in the minimum throttle
valve position (within limits) do not affect engine idle
speeds. This system provides correct idle control under all
conditions. This also means that disconnecting power to
the ECM can result in incorrect idle control or the necessity
to partially press the accelerator when starting until the
ECM relearns idle control.
Engine idle speed is a function of total airflow into the en-
gine based on the IAC valve pintle position, the throttle
valve opening, and the calibrated vacuum loss through ac-
cessories. The minimum throttle valve position is set at the
factory with a stop screw. This setting allows enough air-
flow by the throttle valve to cause the IAC valve pintle to
be positioned a calibrated number of steps (counts) from
the seat during ”controlled” idle operation. The minimum
throttle valve position setting on this engine should not be
considered the ”minimum idle speed,” as on other fuel in-
jected engines. The throttle stop screw is covered with a
plug at the factory following adjustment.
If the IAC valve is suspected as the cause of improper idle
speed, refer to ”Idle Air Control System Check” in this sec-
tion.
MANIFOLD ABSOLUTE PRESSURE
SENSOR
The Manifold Absolute Pressure (MAP) sensor measures
the changes in the intake manifold pressure which result
from engine load and speed changes. It converts these to
a voltage output.

5A1 – 48IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
The Lock up clutch should not apply unless the transaxle
has reached a minimum operating temperature of 8°C
(46°F) TRANS TEMP AND engine coolant temp of 50°C
(122°F).
5. Repeat steps 1–4 using several different throttle
angles.
Part Throttle Detent Downshift
At vehicle steeds of 55 to 65km/h (34 to 40mph) in Fourth
gear, quickly increase throttle angle to greater than 50%.
Verify that :
S TCC apply.
S Transaxle downshift to 3rd gear.
S Solenoid 1 turns ON to OFF.
S Solenoid 2 turns OFF.
Full Throttle Detent Downshift
At vehicle speeds of 55 to 65km/h (34 to 40mph)in Fourth
gear, quickly increase throttle angle to its maximum posi-
tion (100%)
Verify that :
S TCC release.
S Transaxle downshift to Second gear immediately.
S Solenoid 1 turns ON to OFF
S Solenoid 2 turns OFF.
Manual Downshifts
1. At vehicle speeds of 60km/h (40mph)in Fourth
gear, release accelerator pedal while moving gear
selector to Manual Third (3). Observe that :
S Transaxle downshift to Third gear immediately.
S Engine slows vehicle down.
2. Move gear selector back to overdrive(D) and accel-
erate to 31mph (50km/h). Release the accelerator
pedal and move the gear selector to Manual
First(1) and observe that :
S Transaxle downshift to second gear immediate-
ly.
S Engine slows vehicle down
Notice : A Manual First––Third Gear Ratio will occur at
high speeds as an upshift safety feature. Do not attempt
to perform this shift.
Coasting Downshifts
1. With the gear selector in Overdrive(D), accelerate
to Fourth gear with TCC applied.
2. Release the accelerator pedal and lightly apply the
brakes, and observe that :
S TCC release.
S Down shifts occur at speeds shown ON the shift
speed chart.
Manual Gear Range Selection
Upshifts in the manual gear ranges are controlled by the
shift solenoids. Perform the following tests by accelerating
at 25 percent TP sensor increments.
Manual Third (3)
S With vehicle stopped, move the gear selector to
Manual third(3) and accelerate to observe :
– 1–2 shift.
– 2–3 shift.
Manual Second (2)
S With vehicle stopped, move the gear selector to
Manual second(2) and accelerate to observe :
– 1–2 shift.
S Accelerate to 40km/h(25mph) and observe :
– 2–3 shift does not occur
– TCC does not apply
Manual First (1)
S With vehicle stopped, move gear selector to Manu-
al First(1). Accelerate to 30km/h(19mph) and ob-
serve :
– No upshifts occur
Reverse (R)
S With vehicle stopped, move gear selector to R(Re-
verse) and observe :
– Solenoid 1 is OFF
– Solenoid 2 is OFF
Use a scan tool to see if any transaxle trouble codes have
been set. Refer to ”Diagnostic Trouble Codes”in this sec-
tion and repair the vehicle as directed. After repairing the
vehicle, perform the hoist test and verify that the code has
not set again.
If the transaxle is not performing well and no trouble codes
have been set, there may be an intermittent condition.
Check all electrical connections for damage or a loose fit.
You also have to perform a snapshot test which can help
catch an intermittent condition that dose not occur long
enough to set a code.
You may want to read ”Electronic Component Diagnosis”
in this section to become familiar with transaxle conditions
caused by transaxle electrical malfunction.
If no trouble codes have been set and the condition is sus-
pected to be hydraulic, take the vehicle on a road test.
TORQUE CONVERTER LOCK–UP
CLUTCH(TCC) DIAGNOSIS
To properly diagnosis the lock–up clutch(TCC) system,
perform all electrical testing first and then the hydraulic
testing.
The TCC is applied by fluid pressure which is controlled by
a solenoid Located inside the valve body. The solenoid is
energized by completing an electrical circuit through a
combination of switches and sensors.

AISIN AUTOMATIC TRANSAXLE 5A2 – 65
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0741
TORQUE CONVERTER CLUTCH (TCC) CIRCUIT STUCK
OFF
Conditions for Setting the DTC
S Lockup solenoid is stuck OFF.
S D range selected
S Engine water normal temperature
S 20 seconds have passed since the transaxle was
placed in D.
S Engine revolution is 600 rpm or greater.
S No failure of input speed sensor / engine revolution
/ water temperature signal / solenoid electrical /
ranger sensor / throttle signal
Action Taken When the DTC Sets
S TCM will request the illumination of MIL and store
DTC when TCM detects failures on two consecu-
tive ignition cycles.Conditions for Clearing the DTC
S The TCM turns off the MIL when no further failures
detected for three consecutive ignition cycles.
S The scan tool can clear the DTC from the TCM his-
tory.
S The TCM clears the DTC from the TCM history
memory after forty consecutive warm up cycles
without fault.
Cause of Failure
S Lockup solenoid
S Inside A/T
S Inside valve body
S TCM

AISIN AUTOMATIC TRANSAXLE 5A2 – 67
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0742
TORQUE CONVERTER CLUTCH (TCC) CIRCUIT STUCK
ON
Conditions for Setting the DTC
S Lockup solenoid is stuck ON.
S D range selected
S Engine water normal temperature
S 20 seconds have passed since the transaxle was
placed in D.
S Engine revolution is 600 rpm or greater.
S No failure of input speed sensor / engine revolution
/ water temperature signal / solenoid electrical /
ranger sensor / throttle signal
Action Taken When the DTC Sets
S TCM will request the illumination of MIL and store
DTC when TCM detects failures on two consecu-
tive ignition cycles.Conditions for Clearing the DTC
S The TCM turns off the MIL when no further failures
detected for three consecutive ignition cycles.
S The scan tool can clear the DTC from the TCM his-
tory.
S The TCM clears the DTC from the TCM history
memory after forty consecutive warm up cycles
without fault.
Cause of Failure
S Lockup solenoid
S Inside A/T
S Inside valve body
S TCM

AISIN AUTOMATIC TRANSAXLE 5A2 – 75
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0751
SHIFT SOLENOID 1 (SS1) STUCK OFF
Conditions for Setting the DTC
S Shift Solenoid 1 (SS1) is stuck ON/OFF.
S D range selected
S Engine water normal temperature
S 20 seconds have passed since the transaxle was
placed in D.
S Engine revolution is 600 rpm or greater.
S No failure of output speed sensor / input speed
sensor / engine revolution / water temperature sig-
nal / solenoid electrical / ranger sensor / throttle
signal
Action Taken When the DTC SetsS TCM will request the illumination of MIL and store
DTC when TCM detects failures on two consecu-
tive ignition cycles.
Conditions for Clearing the DTC
S The TCM turns off the MIL when no further failures
detected for three consecutive ignition cycles.
S The scan tool can clear the DTC from the TCM his-
tory.
S The TCM clears the DTC from the TCM history
memory after forty consecutive warm up cycles
without fault.
Cause of Failure
S Shift Solenoid 1 (SS1)
S Inside Valve Body
S TCM

5A2 – 80IAISIN AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0756
SHIFT SOLENOID 2 (SS2) STUCK OFF
Conditions for Setting the DTC
S Shift Solenoid 2 (SS2) is stuck ON/OFF.
S D range selected
S Engine water normal temperature
S 20 seconds have passed since the transaxle was
placed in D.
S Engine revolution is 600 rpm or greater.
S No failure of output speed sensor / input speed
sensor / engine revolution / water temperature sig-
nal / solenoid electrical / ranger sensor / throttle
signalAction Taken When the DTC Sets
S TCM will request the illumination of MIL and store
DTC when TCM detects failures on two consecu-
tive ignition cycles.
Conditions for Clearing the DTC
S The TCM turns off the MIL when no further failures
detected for three consecutive ignition cycles.
S The scan tool can clear the DTC from the TCM his-
tory.
S The TCM clears the DTC from the TCM history
memory after forty consecutive warm up cycles
without fault.
Cause of Failure
S Shift Solenoid 2 (SS2)
S Inside Valve Body
S TCM

AISIN AUTOMATIC TRANSAXLE 5A2 – 219
DAEWOO V–121 BL4
Timing Solenoid
Timing solenoid is installed directly in the valve body. The
solenoid operates of ON/OFF by the control signal from
TCM. The solenoid change timing valve of inside the valve
body, operate hydraulic control with apply and drain of for-
ward clutch.
Lock–Up Solenoid
Lock–up solenoid is installed in the valve body. It recieves
control signal from TCM.
Lock–up solenoid operates the lock–up valve inside the
valve body and controls the torque converter lockup func-
tion.
Pressure Control Solenoid (PCS)
The pressure control solenoid (PCS) is located inside the
valve body and regulates the transmission’s fluid pressure
system. It is internally grounded in the TCM and operates
when it is supplied with battery voltage from the TCM,
through the PCS and back to the TCM.
The battery voltage is controlled by a varying current from
the TCM.
The strength of the current is a function of the throttle posi-
tion.
Transmission Fluid Temperature (TFT)
Sensor
TFT sensor provides TCM with information on the trans-
mission fluid temperature.
The TCM uses information from the TFT sensor to calcu-
late the gear shift points and to engage the torque convert-
er lockup function.
Input Shaft Speed (ISS) Sensor
ISS sensor is located on the upper position of the transaxle
and detects A/T input speed from the rotation number of
the direct clutch drum.
They transmit to TCM as a signal.

FIVE–SPEED MANUAL TRANSAXLE 5B – 5
DAEWOO V–121 BL4
DIAGNOSIS
ISOLATE NOISE
Identify the cause of any noise before attempting to repair
the clutch, the transaxle, or their related link–ages.
Symptoms of trouble with the clutch or the manual trans-
axle include:
S A great effort required to shift gears.
S The sound of gears clashing and grinding.
S Gear blockout.
Any of these conditions requires a careful analysis. Make
the following checks before disassembling the clutch or
the transaxle for repairs.
Road Travel Noise
Many noises that appear to come from the transaxle may
actually originate with other sources such as the:
S Tires.
S Road surfaces.
S Wheel bearings.
S Engine.
S Exhaust system.
These noises may vary according to the:
S Size of the vehicle.
S Type of the vehicle.
S Amount of insulation used in the body of the ve-
hicle.
Transaxle Noise
Transaxle gears, like any mechanical device, are not ab-
solutely quiet and will make some noise during normal op-
eration.
To verify suspected transaxle noises:
1. Select a smooth, level asphalt road to reduce tire
and resonant body noise.
2. Drive the vehicle far enough to warm up all the lu-
bricants thoroughly.
3. Record the speed and the gear range of the trans-
axle when the noise occurs.
4. Check for noises with the vehicle stopped, but with
the engine running.
5. Determine if the noise occurs while the vehicle op-
erates in:
S Drive – under a light acceleration or a heavy
pull.
S Float – maintaining a constant speed with a light
throttle on a level road.
S Coast – with the transaxle in gear and the
throttle partly or fully closed.
S All of the above.
Bearing Noise
Differential Side Bearing Noise
Differential side bearing noise and wheel bearing noise
can be confused easily. Since side bearings are pre–
loaded, a differential side bearing noise should not dimin-
ish much when the differential/transaxle is run with the
wheels off the ground.
Wheel Bearing Noise
Wheel bearings produce a rough growl or grating sound
that will continue when the vehicle is coasting and the
transaxle is in NEUTRAL. Since wheel bearings are not
pre–loaded, a wheel bearing noise should diminish con-
siderably when the wheels are off the ground.
Other Noise
Brinelling
A brinelled bearing causes a ”knock” or ”click” approxi-
mately every second revolution of the wheel because the
bearing rollers do not travel at the same speed as the
wheel. In operation, the effect is characterized by a low–
pitched noise.
A brinelled bearing is caused by excessive thrust which
pushes the balls up on the pathway and creates a triangu-
lar–shaped spot in the bearing race. A brinelled bearing
can also be caused from pressing one race into position
by applying pressure on the other race.
A false indication of a brinelled bearing occurs as a result
of vibration near the area where the bearing is mounted.
Brinelling is identified by slight indentations, resulting in a
washboard effect in the bearing race.
Lapping
Lapped bearing noise occurs when fine particles of abra-
sive materials such as scale, sand, or emery circulate
through the oil in the vehicle, causing the surfaces of the
roller and the race to wear away. Bearings that wear loose
but remain smooth, without spalling or pitting, are the re-
sult of dirty oil.
Locking
Large particles of foreign material wedged between the
roller and the race usually causes one of the races to turn,
creating noise from a locked bearing. Pre–loading regular
taper roller bearings to a value higher than that specified
also can result in locked bearings
Pitting
Pitting on the rolling surface comes from normal wear and
the introduction of foreign materials.
Spalling
Spalled bearings have flaked or pitted rollers or races
caused by an overload or an incorrect assembly that re-
sults in a misalignment, a cocking of bearings, or adjust-
ments that are too tight.
After completing these checks, refer to the ”Diagnosis
Chart” in this section.