acc DAEWOO LACETTI 2004 Service Repair Manual

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.

5A1 – 50IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
TCC shudder should only occur during the APPLY and/or
RELEASE of the Lock up clutch.
While TCC Is Applying Or Releasing
If the shudder occurs while TCC is applying, the problem
can be within the transaxle or torque converter.
Something is not allowing the clutch to become fully en-
gaged, not allowing clutch to release, or is trying to release
and apply the clutch at the same time. This could be
caused by leaking turbine shaft seals, a restricted release
orifice, a distorted clutch or housing surface due to long
converter bolts, or defective friction material on the TCC
plate.
Shudder Occurs After TCC Has Applied :
In this case, most of the time there is nothing wrong with
the transaxle! As mentioned above, once the TCC has
been applied, it is very unlikely that will slip. Engine prob-
lems may go unnoticed under light throttle and load, but
become noticeable after TCC apply when going up a hill
or accelerating, due to the mechanical coupling between
engine and transaxle.
Important : Once TCC is applied there is no torque con-
verter assistance. Engine or driveline vibrations could be
unnoticeable before TCC engagement.
Inspect the following components to avoid misdiagnosis of
TCC shudder and possibly disassembling a transaxle and/
or replacing a torque converter unnecessarily :
S Spark plugs – Inspect for cracks, high resistance or
broken insulator.
S Plug wires – Lock in each end, if there is red dust
(ozone) or black substance (carbon) present, then
the wires are bad. Also look for a white discolor-
ation of the wire indicating arcing during hard accel-
eration.
S Distributor cap and rotor – look for broken or un–
crimped parts.
S Coil – look for black on bottom indication arcing
while engine is misfiring.
S Fuel injector – filter may be plugged.
S Vacuum leak – engine won’t get correct amount of
fuel. May run rich or lean depending on where the
leak is.S EGR valve – valve may let it too much unburnable
exhaust gas and cause engine to run lean.
S MAP sensor – like vacuum leak, engine won’t get
correct amount of fuel for proper engine operation.
S Carbon on intake valves – restricts proper flow or
air/fuel mixture into cylinders.
S Flat cam – valves don’t open enough to let proper
fuel/air mixture into cylinders.
S Oxygen sensor – may command engine too rich or
too lean for too long.
S Fuel pressure – may be too low.
S Engine mounts – vibration of mounts can be multi-
plied by TCC engagement.
S Axle joints – checks for vibration.
S TPS – TCC apply and release depends on the TPS
in many engines. If TPS is out of specification, TCC
may remain applied during initial engine starting.
S Cylinder balance – bad piston rings or poorly seal-
ing valves can cause low power in a cylinder.
S Fuel contamination – causes poor engine perfor-
mance.
TCM INITIALIZATION PROCEDURE
When one or more operations such as shown below are
performed, all learned contents which are stored in TCM
memory should be erased after the operations.
S When A/T H/W is replaced in a vehicle,
S When a used TCU is installed in other vehicle,
S When a vehicle condition is unstable (engine RPM
flare, TPS toggling and so on; at this kind of unsta-
ble conditions, mis–adaptation might be done).
1. Connect the Scan 100 with a DLC connector in a
vehicle.
2. Turn ignition switch ON.
3. Turn the power on for the Scan 100.
4. Follow the ”TCM LEARNED INITIALIZE” procedure
on the Scan 100 menu.
Notice : Before pushing ”Yes” Button for TCM initialization
on the Scan 100 screen, make sure that the condition is
as follows:
Condition :
1. Engine idle.
2. Select lever set ”P” range.

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 57
DAEWOO V–121 BL4
Symptom ActionPossible Cause
Sealing Ring Selector ShaftS Check sealing ring.
S Replace sealing ring as described in the repair
instruction.
O–ring at Socket OutletS Check O–ring.
S Replace O–ring as described in the repair in-
struction.
O–ring and Speed Sensor ConnectionS Check O–ring.
S Replace O–ring as described in the repair in-
struction.
Oil Leak Incorrectly IdentifiedS No oil leak is possible at this point.
Speed Sensor Itself Is LeakingS Check speed sensor.
S Replace speed sensor as described in the re-
pair instruction.
Hair Line Crack at the Piping in the Con-
nection Area, Sealing Ring Fit in Trans-
axle HousingS Pressurize the line with compressed air and
check it.
S Replace lines as described in the repair in-
struction.
O–ring Defective, IncorrectCheck O–ring.
Replace O–rings as described in the repair instruc-
tion.
Plug LooseCheck the Tightening Torque for the screw plug.
Tighten to torque specified in the repair instruction.
Noise
SymptomPossible CauseAction
NoiseTFT Level Too LowS When the TFT level is too low, the gear wheels
from the transaxle oil pump might generate
noise.
S Check the TFT level as described in the repair
instruction and fill to the proper level.
Monolith in Catalytic Converter Has
BrokenS Check according to the exhaust gas diagnostic
procedure or by shaking the catalytic converter
casing.
S Replace catalytic converter if necessary.
Noise from Auxiliaries (e.g. exhaust
system, alternator, drive shafts.)S Check these components; if necessary, elimi-
nate the faults as described in the repair in-
struction
Noise from Tires or Wheel BearingsS Eliminate fault if necessary
Noise from Planetary GearsS Whistling noise on traction and overrun(in first
gear only)caused by high rotating speeds(func-
tionally unavoidable)
Cumulative Tooth Backlash in the Com-
plete Drive LineS Production status. Customer must be con-
vinced.
Jerky Noise of the Parking Lock (e.g.
when the car is standing on a gradient)S Load–reversal reaction
S Apply the handbrake before selection the park-
ing Lock (position P)

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

5A1 – 60IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE DIAGNOSIS
DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION
DTCDescriptionIndicationDefault Action
P0562System Voltage LowMIL ONS The TCM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Failure Records buffer.
S Adopt Emergency/Substitute mode and constant 4th
gear by hydraulic control.
S After ignition OFF/ON: 3rd gear by hydraulic control.
Possible P, R and N also possible.
S Power supply cut off to the EDS valve.
P0563System Voltage HighMIL ONS The TCM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Failure Records buffer.
S Adopt Emergency/Substitute mode and constant 4th
gear by hydraulic control.
S After ignition OFF/ON: 3rd gear by hydraulic control.
Possible P, R and N also possible.
S Power supply cut off to the EDS valve.
P0601Internal Control Module
Memory Checksum ErrorMIL ONS The TCM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Failure Records buffer.
S Adopt Emergency/Substitute mode and constant 4th
gear by hydraulic control.
S After ignition OFF/ON : 3rd gear by hydraulic control.
Possible P, R and N also possible.
S Power supply cut off to the EDS valve.
P0603S Internal Control Module
Keep Alive
Memory(KAM)ErrorMIL ONS The TCM will record operating conditions at he time
the diagnostic fails. This information will be stored in
the Failure Records buffer.
S Adopt Emergency/Substitute mode and constant 4th
gear by hydraulic control.
S After ignition OFF/ON: 3rd gear by hydraulic control.
Possible P, R and N also possible.
S Power supply cut off to the EDS valve.
P0604Internal Control Module
Random Access Memory
(RAM) ErrorMIL ONS The TCM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Failure Records buffer.
S Adopt Emergency/ Substitute mode and constant 4th
gear by hydraulic control.
S After ignition OFF/ON : 3rd gear by hydraulic control.
Possible P, R and N also possible.
S Power supply cut off to the EDS valve.
P0606S Transaxle Control Mod-
ule Processor FaultMIL ONS The TCM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Failure Records buffer.
S Adopt Emergency/Substitute mode and constant 4th
gear by hydraulic control.
S After ignition OFF/ON: 3rd gear by hydraulic control.
Possible P, R and N also possible.
S Power supply cut off to the EDS valve.

5A1 – 74IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE(DTC) P0601
INTERNAL CONTROL MODULE MEMORY CHECKSUM
ERROR
Circuit Description
A normal function of the Transmission Control Module
(TCM) programming is to perform an internal check that
verifies the integrity of the RAM memory allocations.
The DTC P0601 sets when the Random Access
Memory(RAM) is not operating correctly when checked on
initialization. An area of RAM is failed a read/ write test.
Conditions For Setting The DTC
S The EEPROM checksum test is separated in two
independent parts, the code checksum test and the
calibration checksum test. For each area the check-
sum is calculated and compared with the corre-
sponding checksum valve. If the valves are differ-
ent, the fault will be set.
S System voltage is too high or too low.
S Transaxle input voltage is too high or too low.
S Immediately after the above condition occurs.
Action Taken When The DTC SetsS The Malfunction Indicator Lamp(MIL) will illuminate.
S The TCM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Failure Records buffer.
S Adopt Emergency/ Substitute mode and constant
4th gear by hydraulic control.
S After ignition OFF/ON : 3rd gear by hydraulic con-
trol. Possible P, R and N also possible.
S Power supply cut off to the EDS valve.
Conditions For Clearing The MIL/DTC
S The MIL will turn OFF when the malfunction has
not occurred after three–ignition cycle.
S A history DTC will clear after 40 consecutive warm
up cycles without a fault.
S Using a scan tool can clear history DTCs.
Diagnostic Aids
S When DTC P0601 sets, the possible cause of fault
could be TCM.

5A1 – 78IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE(DTC) P0604
INTERNAL CONTROL MODULE RANDOM ACCESS
MEMORY(RAM) ERROR
Circuit Description
A normal function of the Transmission Control Module
(TCM) programming is to perform an internal check that
verifies the integrity of the RAM memory allocations.
The DTC P0604 sets when the Random Access
Memory(RAM) is not operating correctly when checked on
initialization. An area of RAM is failed a read/ write test.
Conditions For Setting The DTC
S An area of RAM is failed a read/ write test.
S System voltage is too high or too low.
S Transaxle input voltage is too high or too low.
S Immediately after the above condition occurs.
Action Taken When The DTC Sets
The Malfunction Indicator Lamp(MIL) will illuminate.S The TCM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Failure Records buffer.
S Adopt Emergency/ Substitute mode and constant
4th gear by hydraulic control.
S After ignition OFF/ON : 3rd gear by hydraulic con-
trol. Possible P, R and N also possible.
S Power supply cut off to the EDS valve.
Conditions For Clearing The MIL/DTC
S The MIL will turn OFF when the malfunction has
not occurred after three–ignition cycle.
S A history DTC will clear after 40 consecutive warm
up cycles without a fault.
S Using a scan tool can clear history DTCs.
Diagnostic Aids
S When DTC P0604 sets, the replacement of TCM is
recommended.

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 79
DAEWOO V–121 BL4
DTC P0604 – Internal Control Module Random Access
Memory(RAM) Error
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the check completed?–Go to Step 2Go to ”On–
Board Diagnos-
tic System
Check”
21. Install the scan tool.
2. Turn the ignition ON, with the engine OFF.
Does the scan tool display P0604?–Go to Step 3Go to ”Diag-
nostic Aids”
31. Turn the ignition OFF.
2. Replace the TCM.
Is the action complete?–Go to Step 4–
41. Using the scan tool, clear the DTCs.
2. Road test the vehicle within the conditions for
setting this DTC as specified in the text.
Does the scan tool indicate that this diagnostic has
run and passed?–Go to Step 5Go to Step 2
51. Check if any DTCs are set.
2. Are any DTCs displayed that have not been
diagnosed?–Go to ”Applica-
ble DTC table”System OK