DAEWOO LACETTI 2004 Service Repair Manual

5A1 – 232IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
The ZF 4HP 16 automatic transaxle consists primarily of
the following components.
Mechanical
S Torque converter with TCC
S Drive link assembly
S Two multiple disk clutch assemblies : Clutch B,E
S Three multiple brake assemblies : Brake C,D,F
S Lock–up clutch valve
S Two planetary gear sets
S One oil pump
S Final drive and differential assembly
Electronic
S Two shift solenoid valve(sol.1,2)
S Four pressure control solenoid valve(EDS)
S Two speed sensors : A/T ISS and A/T OSS
S Fluid temperature sensor
S Automatic transaxle control module(TCM)
S Wiring harness assembly
MECHANICAL COMPONENTS
Torque Converter
The converter consists of the impeller, the turbine wheel,
the reaction member (stator) and the oil to transmit torque.
The impeller, which is driven by the engine, causes the oil
in the converter to flow in a circular pattern. This oil flow
meets the turbine wheel, where is direction of flow is de-
flected. At the hub, the oil leaves the turbine and reaches
the reaction member (stator), where it is once again de-
flected so that it reaches the impeller at the correct angle
of flow.
The reversal effect generates movement in the stator, the
reaction torque then amplifies the turbine torque.
The ratio between turbine torque and torque is referred to
as torque multiplication.
The greater the difference is speed between the pump and
turbine, the greater the torque multiplication; it is at its
highest when the turbine is at a standstill. The higher the
speed of the turbine, the lower the torque multiplication.
When the turbine speed reaches about 85%of the pump
speed, torque multiplication=1, i.e. the turbine torque
equivalent to pump torque.
The stator, which bears against the housing via the free-
wheel, is then rotating freely in the oil flow and the free-
wheel is over–come. From this point onwards, the con-
verter acts as a straightforward fluid coupling.
Space Behind Lock–up Clutch Piston
1. Friction lining
2. Lock–up clutch piston
3. Converter cover
4. Turbine wheel
5. Impeller
6. Stator
7. Turbine hub
8. Torque converter impeller hub
Torque Converter Lock–up Clutch (TCC)
The converter lock–up clutch is a device, which eliminates
converter slip and thus helps to improve fuel consumption.
The previous control principle for converter lock–up clutch
operation has been replaced by a controlling function on
the 4 HP 16. The converter lock–up clutch is engaged and
released in a controlled manner. During the controlled
phase, a slight speed difference between the impeller and
turbine wheel is established. This ensures that the en-
gine’s rotating vibration is not phased on to the transaxle.
The result is optimum shift quality.
An electronic pressure–regulating valve determines pres-
sure regulation of the lock–up converter clutch’s piston.
When open (conversion range), 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.

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 233
DAEWOO V–121 BL4
To engage the lock–up clutch, the direction of flow is modi-
fied (reversed) via a valve in the hydraulic selector unit. At
the same time, the space behind the lock–up clutch piston
is vented. The oil pressure passes from the turbine cham-
ber to the lock–up clutch piston and presses it against the
converter’s cover. The turbine is thus blocked by way of
the linings between the piston and cover, and permits rigid
through drive with no slip (or reduced slip if controlled) to
the mechanical stage of the transaxle.
Fluid Pump
The fluid pump is located between the torque converter
and the transaxle case and is driven directly by the torque
converter. The pump sucks the fluid through a filter and de-
livers it to the main pressure regulator valve of the control
system. Excess fluid flows back to the pump. The fluid
pump fulfills the following functions:
S Generates line pressure.
S Delivers fluid under pressure to the torque convert-
er, thus preventing air bubbles in the fluid.
S Induces a flow of fluid through the torque converter
in order to eliminate heat.
S Supplies fluid pressure to the hydraulic control sys-
tem.
S Supplies fluid pressure to the shift components.S Lubricates the transaxle with fluid.
Pump Housing
1. Disc
2. Shaft seal
3. Stator shaft
4. Pump wheel
5. Pump ring gear
6. Dowel pin
Planetary Gears
The ZF 4HP 16 automatic transaxle is equipped with a one
sun gear, 4 planetary gears, planetary carrier, ring gear.
Each gear is located one directly behind the other and are
linked together. In other words, front ring gear is perma-
nently linked to rear planet carrier, front planet carrier is
linked to rear ring gear.
The individual gear ratios are obtained by linking together
the gear set elements in different ways by means of
clutches and brakes.
On the 4HP 16, the power flow is directed into the plane-
tary gear set via rear planet carrier or rear sun gear, or via
both simultaneously, depending on the gear in question.
The output is always via the front planet carrier.

5A1 – 234IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
Shift Elements: Multi–disc Clutches and
Brakes
The purpose of the shift elements is to perform shifts un-
der load without the tractive flow being interrupted.
The shift elements consist of the following.
1. Snap Ring
2. Steel Disc
3. Lined Disc
4. Cup Spring
5. Baffle Plate
6. Disc Carrier
7. Input Shaft
8. Oil Supply to Dynamic Pressure Equalizer
9. Oil Supply to Clutch
10. Cylinder
11. Piston
12. Spring Disc
The shift elements are engaged hydraulically. The pres-
surized oil reaches the space between the cylinder and
piston, as a result the discs are compressed. The clutch/
brake is engaged when the oil pressure drops, the cup
spring acting on the piston presses the piston back into its
initial position. The clutch/brake is now released again.
Depending on the gear, the multi–disc clutches B and E
supply the engine torque to the planetary gear train, with
multi–disc brakes C, D and F directing the torque into the
housing.The dynamic pressure at clutches B and E is equal : i.e.
the dynamic pressure in front of and behind the piston is
equal. This equalizing effect is achieved in the following
way.
The space between the baffle plate and piston is filled with
unpressurized oil. A dynamic pressure dependent on the
engine speed builds up. The space between pressure also
builds up. However, there is simultaneously a static pres-
sure, which causes the clutch to engage. If the static pres-
sure is relieved, the cup spring is able to force the piston
back into its original position.
The advantages of this dynamic pressure equalization
are:
S Reliable clutch opening in all speed ranges
S Smoother shifts.
Parking Lock
The parking lock is actuated via the selector lever when in
position P. It protects the vehicle mechanically against roll-
ing away.
The stop plate is actuated by the selector shaft, which is
permanently connected to the selector lever via a pull
cable. The parking lock pawl on the parking lock gear is
welded onto the lateral shaft of the transaxle and this pre-
vents the drive wheels from turning.
This blocks the driven wheels.
1. Pawl
2. Supporting Bolt
3. Leg Spring

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 235
DAEWOO V–121 BL4
Valve Body
Valve body performs the following tasks:
S Generates the line pressure needed for actuating
the shift elements.
S Actuates the individual shift elements via the clutchvalves.
S Assures limited operation of the automatic trans-
axle in the event of the electronics failing.
S Actuating the lock–up clutch.
S Generating the lubricating pressure for the trans-
axle

5A1 – 236IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
ELECTRONICAL COMPONENTS
Selector Lever/Program Switch
The driver engages the travel position via the selector le-
ver:
P : Park Position
R : Reverse
N : Neutral
D : Forward Speeds
Park/Neutral Position Switch
The Park/Neutral Position Switch is located on the selec-
tor shaft and informs the TCM of the current selector lever
position P–R–N–D–3–2–1.
The selector lever position is transmitted to the TCM in en-
coded form along 4 lines. The encoding is such that mal-
functions in the connecting lead are identified.
The Park/Neutral Position Switch is located on the selec-
tor shaft, which is connected to the selector lever via a pull
cable. In addition, the Park/Neutral Position Switch con-
trols the starter interlock, the reversing light and the selec-
tor lever position indicator on the instrument panel.
Signal Combination
L1L2L3L4
P00120
R00012
N01200
D1212120
31212012
21201212
10121212
Automatic Transaxle Output Speed Sensor
(A/T OSS)
The vehicle A/T OSS is a magnetic inductive pickup that
relays information relative to vehicle speed to the TCM.
Vehicle speed information is used by the TCM to control
shift timing, line pressure, and TCC (lock–up clutch) apply
and release.
The output speed sensor mounts in the case at the speed
sensor rotor, which is pressed onto the spur gear. An air
gap of 0.1mm~1.3mm(0.004~0.05in) is maintained be-
tween the sensor and the teeth on the spur gear teeth. The
sensor consists of a permanent magnet surrounded by a
coil of wire.
As the differential rotates, an AC signal is generated by the
output speed sensor (OSS).
Automatic Transaxle Input Speed Sensor
(A/T ISS)
The A/T ISS is a magnetic inductive pickup that relays in-
formation relative to transaxle input speed to the TCM.
The TCM uses transaxle input speed information to con-
trol line pressure, TCC apply and release and transaxle
shift patterns. This information is also uses to calculate the
appropriate operating gear ratios and TCC slippage.
The input speed sensor mounts onto piston B that is inside
of valve body.
An air gap of 1.8~2.2mm(0.07~0.086inch) is maintained
between the sensor and the piston B.
The sensor consists of a permanent magnet surrounded
by a coil of wire. As the piston B is driven by the turbine
shaft, an AC signal induced in the input speed sensor.
Higher vehicle speeds induce a higher frequency and volt-
age measurement at the sensor.
Sensor resistance should measure between 825~835
ohms at 20°C (68°F). Sensor can measure from
1,000~8,000HZ.

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 237
DAEWOO V–121 BL4
Shift Solenoid Valve: Solenoid 1,2
The shift solenoids are two identical, normally open elec-
tronic exhaust work that control upshifts and downshifts in
all forward gear ranges. These shift solenoids valves to-
gether in a combination of ON and OFF sequences to con-
trol the line pressure and shift mechanisms (clutches,
brakes).
Solenoid 1 controls the high or low of the line pressure
(flow to each clutch valve) by the operation type (ON/
OFF), i.e. solenoid 1is ON, line pressure will be low
(87~116 psi (6~8bar)), solenoid 1 is OFF, line pressure will
be high (232~261 psi (16~18bar)).
Solenoid 2 controls the oil flow to clutch valve E or lockup
clutch valve by the ON/OFF signal.
The TCM monitors numerous inputs to determine the ap-
propriate solenoid state combination and transaxle gear
for the vehicle operating conditions.
Gear
Solenoid 1Solenoid 2
Park, NeutralONON
FirstON/OFFON
SecondON/OFFOFF
ThirdON/OFFOFF
FourthON/OFFOFF
ReverseON/OFFON
Line PressureResistance
Solenoid
valve 1/Sole-
noid valve 2ON(low)
89.9~98.6 psi
(6.2~6.8 bar)
OFF(high)
S 221.9~253.24
psi
S (15.3~17.46
bar)26.5 ± 0.5ohm
Pressure Control Solenoid Valve (EDS
VALVE 3,4,5,6)
The pressure control valve (EDS valve 3,4,5,6) is a preci-
sion electronic pressure regulator that controls the opera-
tion of the clutches, brakes and the lock–up clutch.
The valve reduces the system pressure with which the
downstream solenoid valves and electrical pressure regu-
lating valves are supplied. It is possible to use smaller so-
lenoid valves as a result. The EDS require a constant input
pressure.

5A1 – 238IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
Transaxle Fluid Temperature (TFT) Sensor
The TFT sensor is a positive temperature coefficient
thermistor (temperature sensitive resistor) that provides
information to the TCM regarding transaxle fluid tempera-
ture. The temperature sensor is located in valve body. Cal-
culated temperature is a factor used to determine the shift
time and shift delay time.
The internal electrical resistance of the sensor varies in
relation to the operating temperature of the transaxle fluid
(see chart).
The TCM sends a 5 volt–reference signal to the tempera-
ture sensor and measures the voltage rise in the electrical
circuit. A higher fluid temperature creates a higher resist-
ance in the temperature sensor, thereby measuring a low-
er voltage signal.
The TCM measures this voltage as another input to help
control line pressure, shift schedules and TCC apply.
When transaxle fluid temperature reaches 140°C (284°F)
the TCM enters ”hot mode.” Above this temperature the
TCM modifies transaxle shift schedules and TCC apply in
an attempt to reduce fluid temperature by reducing trans-
axle heat generation. During hot mode the TCM applies
the TCC at all times in fourth gear.
Also, the TCM commands the 2–3 and 3–4 shifts earlier
to help reduce fluid heat generation. Hot mode may not be
available on some applications.
Transaxle Sensor – Temperature To
Resistance To Voltage (approximate)
°C (°F)R high (ohms)R low (ohms)°C (°F)R high (ohms)R low (ohms)
–40 (–40)58655650 (122)1,2061,173
–30 (–22)64161160 (146)1,2951,256
–20 (–4)69967070 (158)1,3881,341
–10 (14)76073280 (176)1,4851,430
0 (32)82579990 (194)1,5851,522
10 (50)893868100 (212)1,6901,617
20 (68)963942110 (230)1,7981,715
25 (77)1,000980120 (248)1,9101,816
30 (86)1,0391,017130 (266)2,0251,920
140 (284)2,1452,027
Transaxle Electrical Connector
The transaxle electrical connector is a very important part
of the transaxle operating system. Any interference with
the electrical connection can cause the transaxle to set
Diagnostic Trouble Codes (DTCs) and/or affect proper op-
eration.
The following items can affect the electrical connections:S Bent pins in the connector from rough handling dur-
ing connection and disconnection.
S Wires backing away from the pins or coming un-
clamped (in either internal or external wiring har-
ness).
S Dirt contamination entering the connector when dis-
connected.
S Pins in the internal wiring connector backing out of
the connector or pushed out during reconnection.

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 239
DAEWOO V–121 BL4
S Excessive transaxle fluid leaking into the connector,
wicking up into the external wiring harness, and
degrading the wire insulation.
S Water/moisture intrusion in the connector.
S Low pin retention in the external connector from
excessive connection and disconnection of the wir-
ing connector assembly.
S Pin corrosion from contamination.
S Broken/cracked connector assembly.
S Points to remember when working with transaxle
wiring connector assembly.
S To remove the connector, squeeze the two tabs
towards each other and pull straight up (refer to
illustration).Carefully limit twisting or wiggling the connector during re-
moval. Bent pins can occur.
DO NOT pry the connector off with a screwdriver or other
tool.
To reinstall the external wiring connector, first orient the
pins by lining up arrows on each half of the connector.
Push the connector straight down into the transaxle with-
out twisting or angling the mating parts.
The connector should click into place with a positive feel
and/or noise.
Transaxle Control Module (TCM)
The transaxle control module (TCM) is an electronic de-
vice which monitors inputs to control various transaxle
functions including shift quality and transaxle sensors,
switches, and components to process for use within its’
control program. Based on this input information, the TCM
controls various transaxle output functions and devices.
Data Link Connector (DLC)
The data link connector (DLC) is a multiple cavity connec-
tor. The DLC provides the means to access serial data
from the TCM to aid in powertrain diagnosis. The DLC al-
lows the technician to use a scan tool to monitor various
systems and display diagnostic trouble codes (DTCs).
The DLC connector is located within the driver’s compart-
ment, directly below the steering column.

5A1 – 240IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
Data Link Connector (CAN TYPE) 1.8L DOHC (Delphi 32 bit)
A Connector (Blue)B Connector (Green)C Connector (Gray)
1Solenoid 2Fluid Temperature GroundSelector Lever Line L1
2Not UsedInput Speed Sensor (+)Not Used
3Pressure Control Solenoid Valve
(EDS 4)BAT +Not Used
4TFT SensorInput Speed Sensor (–)Hold Mode Switch
5Stoplamp SwitchOutput Speed Sensor (–)Not Used
6Hold Mode IndicatorSelector Lever Line L3EDS Supply
7DLCInput Speed Sensor GroundEDS Supply
8CAN HighSpeedometerSolenoid Supply
9Solenoid 1Not UsedNot Used
10Pressure Control Solenoid Valve
(EDS 5)Output Speed Sensor (+)Not Used
11Pressure Control Solenoid Valve
(EDS 3)Selector Lever Line L4Not Used
12Pressure Control Solenoid Valve
(EDS 6)GroundNot Used
13Not UsedGroundNot Used
14Not UsedNot UsedNot Used
15Not UsedSelector Lever Line L2IG ON
16CAN LowNot UsedIG ON

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 241
DAEWOO V–121 BL4
TCM INPUTS THAT AFFECT THE 4HP
16 TRANSAXLE
Throttle Position Sensor
S Provides throttle position data to the TCM for deter-
mining shift patterns and TCC apply/release.
S An incorrect throttle position sensor input could
causes erratic or shift pattern, poor shift quality or
TCC function
Automatic Transaxle Output (Shaft) Speed
Sensor
S Provides vehicle speed data to the TCM for deter-
mining shift patterns and TCC apply/release, and
gear ratio calculations.
S An incorrect throttle position sensor input could
causes erratic or shift pattern, poor shift quality or
TCC function
Automatic Transaxle Input (Shaft) Speed
Sensor
S Provides transaxle input speed data to the TCM for
determining shift patterns and TCC apply/release,
and gear ratio.
Engine Coolant Temperature Sensor
S Provides coolant temperature data to the TCM for
determining initial TCC engagement.
S An incorrect engine coolant temperature sensor
input could causes an incorrect initial TCC apply
Engine Speed
S The ignition module provides engine speed data the
TCM.
S The TCM uses engine speed information for con-
trolling wide open throttle shifts and the TCC PWM
solenoid duty cycle.
Stoplamp Switch
S Provides brake apply information to the TCM for
controlling TCC apply and release.
S An incorrect TCC stoplamp switch input could
causes an incorrect TCC apply or release.
Transaxle Fluid Temperature (TFT) Sensor
S Provides transaxle fluid temperature information to
the TCM for determining alternate shift patterns and
TCC apply during high temperature conditions (hot
mode operation).
S An incorrect transaxle temperature sensor input
could causes altered shift patterns, poor shift quali-
ty and incorrect TCC apply.