2004 DAEWOO LACETTI transaxle

1F – 568IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1601
SPI COMMUNICATIONS BETWEEN ECM AND TCM
Circuit Description
The Serial Peripheral Interface (SPI) communication is
used internally by the Engine Control Module (ECM) to
send message between the engine processor and the au-
tomatic transaxle processor. Included in each message
sent between the two processor is a checksum of the mes-
sage. Both the engine processor automatic transaxle
processor will compare this checksum value with calcu-
lated checksum. If the checksum do not match, the proc-
essor will review the new data as being corrupted and ig-
nore the value. The processor then use the previous
message. The receiving processor will then send a mes-
sage to the sending processor informing it that its last mes-
sage was corrupted.
The ECM monitor periodic TCM status message and if
message is not received fail counter incremented and
Diagnostic trouble Code (DTC) will stored.
Conditions for Setting the DTC
S Ignition switch is turned to ON.S Ignition voltage is greater than 11 volts.
S Engine is running more than 2 seconds.
S Device Control not active.
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 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 P1601 SPI Communications Between ECM and TCM
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”
21. Turn the ignition OFF.
2. Replace the Engine Control Module (ECM).
Is the repair complete?–Go to Step 3–
31. Using the scan tool, clear the Diagnostic
Trouble Codes (DTCs).
2. Start the engine and idle at normal operating
temperature.
3. Operate the vehicle within the Conditions for
setting this DTC as 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 – 581
DAEWOO V–121 BL4
LACK OF POWER, SLUGGISHNESS, OR SPONGINESS
Definition : The engine delivers less than expected power. There is little or no increase in speed when the accelerator pedal
is partially applied.
Step
ActionValue(s)YesNo
1Were the Important Preliminary Checks performed?–Go toStep 2Go to
”Important Pre-
liminary
Checks”
21. Verify the customer’s complaint.
2. Compare the performance of the customer’s
vehicle with a similar unit.
Does the problem exist?–Go toStep 3System OK
31. Inspect the air filter for excessive contamina-
tion.
2. Replace the air filter as needed.
3. Check the transaxle shift pattern and downshift
operation.
Does the transaxle operate properly?–Go toStep 4Go toStep 5
4Check the fuel system pressure.
Is the fuel system pressure within specifications?41–47 psi
(284–325 kPa)Go toStep 7Go toStep 6
5Repair the transaxle as needed.
Is the repair complete?–System OK–
6Repair the fuel system as needed.
Is the repair complete?–System OK–
7Check for a restricted fuel filter or contaminated fuel.
Is the problem found?–Go toStep 8Go toStep 9
8Repair or replace any components as needed.
Is the repair complete?–System OK–
91. Check the ignition system output for all of the
cylinders using a spark tester.
2. Check for proper ignition control operation.
Is the ignition system operating properly?–Go toStep 10Go toStep 11
101. With the engine at normal operating tempera-
ture, connect a vacuum gauge to a vacuum
port on the intake manifold.
2. Operate the engine at 1,000 rpm.
3. Record the vacuum reading.
4. Increase the engine speed to 2,500 rpm.
5. Note the vacuum reading at a steady 2,500
rpm.
Does the vacuum decrease more than the value
specified?10 kPa
(3 in. Hg)Go toStep 12Go toStep 15
11Repair or replace any ignition system components
as needed.
Is the repair complete?–System OK–
12Inspect the exhaust system for restrictions and dam-
aged or collapsed pipes.
Is the problem found?–Go toStep 13Go toStep 15
13Repair or replace any components as needed.
Is the repair complete?–System OK–

ENGINE CONTROLS 1F – 587
DAEWOO V–121 BL4
POOR FUEL ECONOMY
Definition : Fuel economy, as measured by an actual road
test, is noticeably lower than expected. Also, fuel econo-
my is noticeably lower than it was on this vehicle at one
time, as previously shown by an actual road test.
Important : Driving habits affect fuel economy. Check the
owner’s driving habits by asking the following questions:1. Is the A/C system (i.e. defroster mode) turned on
all the time?
2. Are the tires at the correct air pressure?
3. Have excessively heavy loads been carried?
4. Does the driver accelerate too much and too often?
Suggest the driver read the section in the owner’s
manual about fuel economy.
Step
ActionValue(s)YesNo
1Were the Important Preliminary Checks performed?–Go toStep 2Go to
”Important Pre-
liminary
Checks”
21. Inspect the air filter for excessive contamina-
tion.
2. Inspect for fuel system leaks.
Are all needed checks complete?–Go toStep 3–
31. Inspect the spark plugs for excessive wear,
insulation cracks, improper gap, or heavy de-
posits.
2. Replace any faulty spark plugs.
3. Inspect the ignition wires for cracking, hard-
ness, and proper connections.
Are all needed checks and repairs complete?–Go toStep 4–
41. Inspect the engine coolant level.
2. Check the thermostat for being always open or
for an incorrect heat range.
3. Replace the thermostat as needed.
Are all needed checks and repairs complete?–Go toStep 5–
51. Check the transaxle shift pattern. Ensure all
transaxle gears are functioning.
2. Check the Torque Converter Clutch (TCC) op-
eration with a scan tool. The scan tool should
indicate rpm drop when the TCC is command-
ed on.
3. Check for proper calibration of the speedome-
ter.
4. Check the brakes for dragging.
5. Check the cylinder compression.
6. Repair, replace, or adjust any components as
needed.
Are all checks and needed repairs complete?–System OK–

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.

2C – 2IFRONT SUSPENSION
DAEWOO V–121 BL4
SPECIFICATIONS
GENERAL SPECIFICATIONS
ApplicationTrim Height
Center of Front Wheel to Bottom of Front Wheel Well368 mm (14.4 in.)
Center of Rear Wheel to Bottom of Rear Wheel Well367 mm (14.4 in.)
* CONDITION : Full Fuel in the Tank
FASTENER TIGHTENING SPECIFICATIONS
ApplicationNSmLb–FtLb–In
Ball Joint Pinch Bolt Nut6044–
Ball Joint–to–Control Arm Nuts10074–
Front Control Arm–to–Crossmember Bolt12592–
Rear Contral Arm–to–Crossmember Bolt11 081–
Crossmember Link–to–Crossmember Bolt11 484–
Crossmember Link–to–Transaxle Bracket Nut169125–
Drive Axle–to–Hub Caulking Nut300221–
Front Crossmember–to–Body Bolts13096–
Piston Rod Nut7555–
Rear Crossmember–to–Body Bolts196145–
Stabilizer Link–to–Strut Assembly Nut4735–
Stabilizer Shaft–to–Crossmember Clamp Bolts2518–
Stabilizer Shaft–to–Stabilizer Link Nut4735–
Steering Knuckle–to–Strut Assembly Nuts/Bolts12089–
Strut Assembly–to–Body Nut6548–

2C – 18IFRONT SUSPENSION
DAEWOO V–121 BL4
3. Connect the stabilizer shaft link to the strut assem-
bly by attaching the stabilizer link–to–strut assem-
bly nut.
Tighten
Tighten the stabilizer link–to–strut assembly nut to 47
NSm (35 lb–ft).
4. Install the brake line to the securing bracket on the
strut assembly.
5. On vehicles equipped with the ABS, connect the
ABS sensor line to the strut assembly.
6. Install the wheel. Refer to Section 2E, Tires and
Wheels.
7. Lower the vehicle.
8. Install the nuts securing the strut assembly to the
body of the vehicle.
Tighten
Tighten the strut assembly–to–body nuts to 65 NSm
(48 lb–ft).
CROSSMEMBER ASSEMBLY
Removal Procedure
1. Raise and suitably support the vehicle.
2. Remove the wheels. Refer to Section 2E, Tires and
Wheels.
3. Remove the nuts and bolts from the steering gear
mounting bracket.
4. Remove the return line bolt from the clip on the
crossmember.
5. Remove the exhaust pipe forward of the catalytic
converter. Refer to Section 1G, Engine Exhaust.
6. Disconnect the tie rod from the knuckle assembly.
Refer to Section 6C, Power Steering Gear.
7. Disconnect the ball joint from the knuckle assembly.
Refer to ”Knuckle Assembly” in this section.
8. Disconnect the stabilizer link from the strut assem-
bly. Refer to ”Stabilizer Link” in this section.
9. Remove the crossmember link–to–transaxle brack-
et nut.
1) Remove the right lower engine mount.
2) Remove the rear transmission mount bracket.

2C – 20IFRONT SUSPENSION
DAEWOO V–121 BL4
6. Install the crossmember link–to–transaxle bracket
nut.
Tighten
Tighten the crossmember link–to–transaxle bracket
nut to 169 NSm (125 lb–ft).
7. Connect the stabilizer link to the strut assembly.
Refer to ”Stabilizer Link” in this section.
8. Connect the ball joint to the knuckle assembly. Re-
fer to ”Knuckle Assembly” in this section.
9. Connect the tie rod from the knuckle assembly. Re-
fer to Section 6C, Power Steering Gear.
10. Install the exhaust pipe into the vehicle. Refer to
Section 1G, Engine Exhaust.
11. Install the wheels. Refer to Section 2E, Tires and
Wheels.
12. Lower the vehicle.

SECTION : 3A
AUTOMATIC TRANSAXLE DRIVE AXLE
TABLE OF CONTENTS
SPECIFICATIONS3A–1 . . . . . . . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specifications 3A–1. . . . . . . . . .
SPECIAL TOOLS3A–2 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Tools Table 3A–2. . . . . . . . . . . . . . . . . . . . . . . .
COMPONENT LOCATOR3A–2 . . . . . . . . . . . . . . . . . . . .
Front Drive Axle 3A–2. . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE AND REPAIR3A–4 . . . . . . . . . . . . . . . ON–VEHICLE SERVICE 3A–4. . . . . . . . . . . . . . . . . . . . .
Drive Axle Assembly 3A–4. . . . . . . . . . . . . . . . . . . . . . .
UNIT REPAIR 3A–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Outer Joint Seal 3A–7. . . . . . . . . . . . . . . . . . . . . . . . . .
Inner Tripot Seal 3A–8. . . . . . . . . . . . . . . . . . . . . . . . . .
GENERAL DESCRIPTION AND SYSTEM
OPERATION3A–10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Drive Axle 3A–10. . . . . . . . . . . . . . . . . . . . . . . . . .
SPECIFICATIONS
FASTENER TIGHTENING SPECIFICATIONS
ApplicationNSmLb–FtLb–In
Axle Shaft Caulking Nut300221–
Lower Ball Joint Pinch Bolt and Nut6044–
Tie Rod Nut5541–
Wheel Nuts10074–