2004 DAEWOO LACETTI torque

5A1 – 24IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
Drive Range – Second Gear
In Drive 2, the transaxle drive is via the input shaft and
clutch E. The elements of this transaxle function are as fol-
lows:
S Clutch E is applied to drive the front ring gear.
S The front ring gear drives the front planetary gear
carrier.
S The front planetary gear carrier drives the differen-
tial pinion gear clockwise.
S Brake F is applied holding the front sun gear sta-
tionary.
Control
Clutch E Engaged
Solenoid 2 will be switched OFF. Line pressure, which is
supplied by the reduction valve, flows to the inlet port of
clutch valve E. Fluid will then pass through the clutch valve
and clutch E will engage.Clutch F Engaged
EDS 5 will be switched ON. The line pressure, which
passed through the reduction valve, will flow to the holding
valve and the clutch valve inlet. As a result the valve spool
is depressed.
Lock–up Clutch
Solenoid valve 2 is turned ON and the line pressure control
valve 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.

5A1 – 26IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
Drive Range – Third Gear
In Drive 3, transaxle drive is via the input shaft to clutches
B and E. The elements of this transaxle function are as fol-
lows:
S Clutches B and E are engaged to drive the rear sun
gear and rear planetary gear carrier clockwise.
S The clockwise rotation of the rear sun gear and rear
planetary gear carrier will cause the front planetary
gear to rotate in the same direction.
Control
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 valve 2 is turned ON and the line pressure control
valve 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.

5A1 – 28IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
Drive Range – Fourth Gear
In Drive 4, transaxle drive is via the input shaft and
clutches E and C. The elements of this transaxle function
are as follows:
S Clutch E is engaged to drive the rear planetary gear
carrier.
S The rear planetary gear carrier drives the rear ring
gear.
S The rear ring gear carrier drives the differential
gear.
Control
Clutch E Engaged
Solenoid 2 will be switched OFF. Line pressure, which is
supplied by the reduction valve, flows to the inlet port of
clutch valve E. Fluid will then pass through the clutch valve
and clutch E will engage.Clutch C Engaged
EDS 4 will be switched OFF causing the fluid level to be
high. Line pressure will be directed to the safety valve,
clutch valve D and holding valve D. Clutch valve C and
holding valve C will engage as pressure flows through the
safety valve.
Lock–up Clutch
Solenoid valve 2 is turned ON and the line pressure control
valve 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.

5A1 – 34IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
TORQUE CONVERTER
1. Torque Converter Housing
2. Torque Converter
3. Torque Converter Gasket
4. Steel Gasket
5. Oil Baffle Plate
6. Bolt
7. Magnet
8. Oil Filter
9. O–ring10. Screw
11. Pressure Plug
12. Pressure Plug
13. Oil Drain Plug
14. Oil Level Plug
15. Screw
16. Bolt
17. Bolt

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 45
DAEWOO V–121 BL4
CLUTCH PLATE DIAGNOSIS
Composition Plates
Dry the plate and inspect the plates for the following condi-
tions :
S Pitting
S Flaking
S Wear
S Glazing
S Cracking
S Charring
Chips or metal particles embedded in the lining
Replace a composition plate which shows any of these
conditions.
Steel Plates
Wipe the plates dry and check the plates for heat discolor-
ation. If the surfaces are smooth, even if colorsmear is in-
dicated, you can reuse the plate. If the plate is discolored
with hot spots or if the surface is scuffed, replace the plate.
Important : If the clutch shows evidence or extreme heat
or burning, replace the springs.
Causes of Burned Clutch Plates
The following conditions can result in a burned clutch
plate:
S Incorrect usage of clutch plates.
S Engine coolant in the transaxle fluid.
S A cracked clutch piston.
S Damaged or missing seals.
S Low line pressure.
S Valve problems.
– The valve body face is not flat
– Porosity between channels
– The valve bushing clips are improperly installed.
– The check balls are misplaced.
S The seal rings are worn or damaged
Engine Coolant in Transaxle
Notice : Antifreeze will deteriorate the O–ring seals and
the glue used to bond the clutch material to the pressure
plate. Both conditions may cause transaxle damage.
Perform the following steps if the transaxle oil cooler has
developed a leak, allowing engine coolant to enter the
transaxle:
1. Because the coolant will attach to the seal material
causing leakage, disassemble the transaxle and
replace all rubber type seals.
2. Because the facing material may become sepa-
rated from the steel center portion, replace the
composition faced clutch plate assemblies.
3. Replace all nylon parts including washers.
4. Replace the torque converter.
5. Thoroughly clean and rebuild the transaxle, using
new gaskets and oil filter.6. Flush the cooler lines after you have properly re-
paired or replaced the transaxle.
COOLER FLUSHING AND FLOW
TEST
Notice : You must flush the cooler whenever you receive
a transaxle for service. Cooler flushing is essential for
SRTA installation, major overhaul, whenever you replace
a pump or torque converter, or whenever you suspect that
the fluid has been contaminated.
After filling the transaxle with fluid, start the engine and run
for 30 seconds. This will remove any residual moisture
from the oil cooler. Disconnect the return line at the trans-
axle and observe the flow with the engine running. If the
fluid flow is insufficient, check the fluid flow by disconnect-
ing the feed line at the cooler. Observe the flow with the
engine running.
S If the flow from the cooler return line at the trans-
axle is insufficient, check the flow rate from the feed
line to the cooler. BLockage exists in the transaxle
or the cooler.
S If the flow from the transaxle feed line to the cooler
is insufficient, the transaxle is the cause of the fluid
flow problem.
S If the flow the transaxle feed line to the cooler is
insufficient, but flow from the cooler return line to
the transaxle is insufficient, inspect the cooler pipes
and fittings. Then repeat the cooler flushing proce-
dure. If the flow is still insufficient, replace the cool-
er.
TRANSAXLE FLUID LEVEL SERVICE
PROCEDURE
This procedure is to be used when checking a concern
with the fluid level in a vehicle. A low fluid level will result
in slipping and loss of drive/ reverse or delay on engage-
ment of drive/ reverse when the vehicle is cold.
The vehicle is first checked for transaxle diagnostic mes-
sages on the scan tool. If the oil level is low, it is possible
to register a vehicle speed signal fault.
The vehicle is to be test driven to determine if there is an
abnormal delay when selecting drive or reverse, or loss of
drive. One symptom of low fluid level is a momentary loss
of drive when driving the vehicle around a corner. Also
when the transaxle fluid level is low, a loss of drive may oc-
cur when the transaxle fluid temperature is low.
When adding or changing transaxle fluid use only ESSO
LT 71141 automatic transaxle fluid or other approved
fluids. The use of incorrect fluid will cause the performance
and durability of the transaxle to be severely degraded.
Fluid Level Diagnosis Procedure
1. If the vehicle is at operating temperature allow the
vehicle to cool down for two hours, but no greater
than four hours. Or if the vehicle is at cool status,
start the engine and allow the engine to idle for
approximately 5 minutes (825~875 rpm), if pos-

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 – 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.

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 49
DAEWOO V–121 BL4
Functional Check Procedure
Inspect
1. Install a tachometer or scan tool.
2. Operate the vehicle unit proper operating tempera-
ture is reached.
3. Drive the vehicle at 80 to 88km/h (50 to 55 mph)
with light throttle(road load).
4. Maintaining throttle position, lightly touch the brake
pedal and check for release of the TCC and a slight
increase in engine speed(rpm).
5. Release the brake slowly accelerate and check for
a reapply of the Lock up clutch and a slight de-
crease in engine speed(rpm).
Torque Converter Evaluation
Torque Converter Stator
The torque converter stator roller clutch can have one of
two different type malfunctions :
A. Stator assembly freewheels in both directions.
B. Stator assembly remains Locked up at all times.
Condition A – Poor Acceleration Low
Speed
The car tends to have poor acceleration from a stand still.
At speeds above 50 to 55km/h(30 to 35mph), the car may
act normal. If poor acceleration is noted, it should first be
determined that the exhaust system is not blocked, and
the transaxle is in 1st(First) gear when starting out.
If the engine freely accelerates to high rpm in N(Neutral),
it can be assumed that the engine and exhaust system are
normal. Checking for poor performance in ”Drive” and ”Re-
verse” will help determine if the stator is freewheeling at all
times.
Condition B – Poor Acceleration High
Speed
Engine rpm and car speed limited or restricted at high
speeds. Performance when accelerating from a standstill
is normal. Engine may overheat. Visual examination of the
converter may reveal a blue color from overheating.
If the converter has been removed, the stator roller clutch
can be checked by inserting two fingers into the splined in-
ner race of the roller clutch and trying to turn freely clock-
wise, but not turn or be very difficult to turn counter clock-
wise.
Noise
Torque converter whine is usually noticed when the ve-
hicle is stopped and the transaxle is in ”Drive” or ”Re-
verse”. The noise will increase when engine rpm is in-
creased. The noise will stop when the vehicle is moving or
when the torque converter clutch is applied because both
halves of the converter are turning at the same speed.
Perform a stall test to make sure the noise is actually com-
ing from the converter :1. Place foot on brake.
2. Put gear selector in ”Drive”.
3. Depress accelerator to approximately 1200rpm for
no more than six seconds.
Notice : If the accelerator is depressed for more than six
seconds, damage to the transaxle may occur.
A torque converter noise will increase under this load.
Important : This noise should not be confused with pump
whine noise which is usually noticeable in P (Park), N
(Neutral) and all other gear ranges. Pump whine will vary
with pressure ranges.
The torque converter should be replaced under any of the
following conditions:
S External leaks in the hub weld area.
S Converter hub is scored or damaged.
S Converter pilot is broken, damaged or fits poorly
into crankshaft.
S Steel particles are found after flushing the cooler
and cooler lines.
S Pump is damaged or steel particles are found in the
converter.
S Vehicle has TCC shudder and/or no TCC apply.
Replace only after all hydraulic and electrical diag-
noses have been made.(Lock up clutch material
may be glazed.)
S Converter has an imbalance which cannot be cor–
rected. (Refer To Converter Vibration Test Proce-
dure.)
S Converter is contaminated with engine coolant con-
taining antifreeze.
S Internal failure of stator roller clutch.
S Excess end play.
S Heavy clutch debris due to overheating (blue con-
verter).
S Steel particles or clutch lining material found in fluid
filter or on magnet when no internal parts in unit are
worn or damaged(indicates that lining material
came from converter).
The torque converter should not be replace if :
S The oil has an odor, is discolored, and there is no
evidence of metal or clutch facing particles.
S The threads in one or more of the converter bolt
holes are damaged.
–correct with thread insert.
S Transaxle failure did not display evidence of dam-
age or worn internal parts, steel particles or clutch
plate lining material in unit and inside the fluid filter.
S Vehicle has been exposed to high mileage(only).
The exception may be where the Lock up clutch
damper plate lining has seen excess wear by ve-
hicles operated in heavy and/or constant traffic,
such as taxi, delivery or police use.
Lock–Up Clutch Shudder Diagnosis
The key to diagnosing lock–up clutch(TCC) shudder is to
note when it happens and under what conditions.