
IBefore assembly, apply a coat of recommended ATF to all parts. Apply petroleum jelly to protect O-rings
and seals, and to hold bearings and washers in place during assembly. Do not use grease.
I Extreme care should be taken to avoid damage to O-rings, seals and gaskets when assembling.
I After overhaul, refill the transmission with new ATF.
I When the A/T drain plug is removed, only some of the fluid is drained. Old A/T fluid will remain in torque
converter and ATF cooling system.
Always follow the procedures under ªChanging A/T Fluidº in the MA section when changing A/T fluid.
Service Notice or Precautions
FAIL-SAFE
The TCM has an electronic Fail-Safe (limp home mode). This allows the vehicle to be driven even if a major
electrical input/output device circuit is damaged.
Under Fail-Safe, the vehicle always runs in third gear even with a shift lever position of ª1º, ª2º or ªDº. Cus-
tomer may complain of ªsluggish or poor accelerationº.
When the Fail-Safe operation occurs the next time the key is turned to the ªONº position, the SPORT indica-
tor lamp will blink for about 8 seconds. (For diagnosis, refer to AT-33.)
Fail-Safe may activate without electrical circuit damages if the vehicle is driven under extreme conditions (such
as excessive wheel spins and emergency braking immediately afterwards). In this case, turn the ignition key
ªOFFº for 5 seconds and then ªONº to recover normal shift pattern.
The blinking of the SPORT indicator lamp for about 8 seconds will appear only once and be cleared. The cus-
tomer may resume normal driving conditions by chance.
Always follow the ªWORK FLOWº (Refer to AT-26).
The SELF-DIAGNOSIS results will be as follows:
The first SELF-DIAGNOSIS will indicate the damage of the vehicle speed sensor or the revolution sensor.
During the next SELF-DIAGNOSIS performed after checking the sensor, no damages will be indicated.
PREPARATION AND PRECAUTIONS
Precautions (Cont'd)
AT- 5
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Control System
OUTLINE
The automatic transmission senses vehicle operating conditions through various sensors. It always controls
the optimum shaft position and reduces shifting and lock-up shocks.
SENSORSTCMACTUATORS
Park/neutral position switch
Throttle (accelerator) position
sensor
Closed throttle position switch
Wide open throttle position
switch
Engine speed signal
A/T fluid temperature sensor
Revolution sensor
Vehicle speed sensor
Overdrive control switch
A/T mode switch
E
Shift control
Line pressure control
Lock-up control
Overrun clutch control
Timing control
Fail-safe control
Self-diagnosis
Duet-EU control
CONSULT-II communication line
control
E
Shift solenoid valve A
Shift solenoid valve B
Overrun clutch solenoid valve
Torque converter clutch
solenoid valve
Line pressure solenoid valve
O/D OFF or SPORT indicator
lamp
CONTROL SYSTEM
NAT230
OVERALL SYSTEM
AT-12
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TCM FUNCTION
The function of the TCM is to:
IReceive input signals sent from various switches and sensors.
I Determine required line pressure, shifting point, lock-up operation, and engine brake operation.
I Send required output signals to the respective solenoids.
INPUT/OUTPUT SIGNAL OF TCM
Sensors and solenoid valves Function
Input Park/neutral position switch
Detects select lever position and sends a signal to TCM.
Throttle (accelerator) position sensor Detects throttle valve position and sends a signal to TCM.
Closed throttle position switch Detects throttle valve's fully-closed position and sends a signal to TCM.
Wide open throttle position switch Detects a throttle valve position of greater than 1/2 of full throttle and sends a
signal to TCM.
Engine speed signal From ECM.
A/T fluid temperature sensor Detects transmission fluid temperature and sends a signal to TCM.
Revolution sensor Detects output shaft rpm and sends a signal to TCM.
Vehicle speed sensor Used as an auxiliary vehicle speed sensor. Sends a signal when revolution sen-
sor (installed on transmission) malfunctions.
Overdrive control switch
A/T mode switch Sends a signal, which prohibits a shift to ªD
4º (overdrive) position, to the TCM.
Output Shift solenoid valve A/B
Selects shifting point suited to driving conditions in relation to a signal sent from
TCM.
Line pressure solenoid valve Regulates (or decreases) line pressure suited to driving conditions in relation to
a signal sent from TCM.
Torque converter clutch solenoid valve Regulates (or decreases) lock-up pressure suited to driving conditions in relation
to a signal sent from TCM.
Overrun clutch solenoid valve Controls an ªengine brakeº effect suited to driving conditions in relation to a sig-
nal sent from TCM.
O/D OFF indicator lamp
SPORT indicator lamp Shows TCM malfunctions, when A/T control components malfunction.
OVERALL SYSTEM
Control System (Cont'd)
AT-13
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Self-diagnosis
After performing this procedure, place check marks for results on
the ªDIAGNOSTIC WORKSHEETº, AT-24. Reference pages are
provided following the items.
SELF-DIAGNOSTIC PROCEDURE (With CONSULT-II)
1. Turn on CONSULT-II and touch ªA/Tº.If A/T is not displayed, check TCM power supply and ground
circuit. Refer to AT-46. If result is NG, refer to EL section
(ªPOWER SUPPLY ROUTINGº).
2. Touch ªSELF-DIAG RESULTSº. Display shows malfunction experienced since the last erasing
operation.
CONSULT-II performs REAL-TIME SELF-DIAGNOSIS.
Also, any malfunction detected while in this mode will be dis-
played at real time.
Item Display DescriptionRemarks
No failure ****NO FAILURE
****I
No failure has been detected.
Initial start *INITIAL START
*I
This is NOT a malfunction message.
Whenever shutting off a power supply to the
TCM, this message appears on the screen.
[]
Vehicle speed
sensor×A/T
(Revolution sensor) VHCL SPEED SEN×A/T I
No signal input from vehicle speed sensor×A/T (revolution
sensor) during traveling due to disconnection, or input of
abnormal signal.
Vehicle speed
sensor×MTR (Meter) VHCL SPEED SEN×MTR I
No signal input from vehicle speed sensor×MTR during
traveling due to disconnection, or input of abnormal signal.
Throttle (accelerator)
position sensor THROTTLE POSI SEN I
Throttle (accelerator) position sensor signal voltage is
abnormally high.
I Throttle (accelerator) position sensor signal voltage is
abnormally low with closed throttle position switch ªOFFº
or wide open throttle position switch ªONº.
Shift solenoid valve A SHIFT SOLENOID/V A I
Specified voltage is not applied to solenoid valve due to
disconnection or shortcircuit.
Shift solenoid valve B SHIFT SOLENOID/V B I
Specified voltage is not applied to solenoid valve due to
disconnection or shortcircuit.
Overrun clutch
solenoid valve OVERRUN CLUTCH S/V I
Specified voltage is not applied to solenoid valve due to
disconnection or shortcircuit.
T/C clutch solenoid
valve T/C CLUTCH SOL/V I
Specified voltage is not applied to solenoid valve due to
disconnection or shortcircuit.
A/T fluid temperature
sensor/TCM power
source BATT/FLUID TEMP SEN I
Supply voltage to TCM is abnormally low during traveling.
I Fluid temperature signal voltage is abnormally high
(fluid temperature is low) during traveling. To be dis-
played in case
of abnormality
and no record-
ing is made
Engine speed signal ENGINE SPEED SIG
IEngine RPM is abnormally low during traveling.
Line pressure
solenoid valve LINE PRESSURE S/V I
Specified voltage is not applied to solenoid valve due to
disconnection or shortcircuit.
TCM (ROM) CONTROL UNIT (ROM) ITCM memory (ROM) is malfunctioning.
TCM (RAM) CONTROL UNIT (RAM) ITCM memory (RAM) is malfunctioning.
SAT014K
SAT987J
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
AT-14
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JUDGEMENT OF SELF-DIAGNOSIS CODE
SPORT indicator lamps
All judgement flickers are same.
SAT819H
All circuits that can be confirmed by self-diagnosis are OK.
4th judgement flicker is longer than others.
SAT797H
Shift solenoid valve A circuit is short-circuited or discon-
nected.
Go to SHIFT SOLENOID VALVE A, AT-65.
1st judgement flicker is longer than others.
SAT794H
Revolution sensor circuit is short-circuited or disconnected.
Go to VEHICLE SPEED SENSOR ×A/T (REVOLUTION
SENSOR), AT-52.
5th judgement flicker is longer than others.
SAT798H
Shift solenoid valve B circuit is short-circuited or discon-
nected.
Go to SHIFT SOLENOID VALVE B, AT-68.
2nd judgement flicker is longer than others.
SAT795HVehicle speed sensor circuit is short-circuited or discon-
nected.
Go to VEHICLE SPEED SENSOR ×MTR, AT-56.
6th judgement flicker is longer than others.
SAT799H
Overrun clutch solenoid valve circuit is short-circuited or dis-
connected.
Go to OVERRUN CLUTCH SOLENOID VALVE, AT-71.
3rd judgement flicker is longer than others.
SAT796H
Throttle (accelerator) position sensor circuit is short-circuited
or disconnected.
Go to THROTTLE (ACCELERATOR) POSITION
SENSOR, AT-62.
7th judgement flicker is longer than others.
SAT800H
Torque converter clutch solenoid valve circuit is short-cir-
cuited or disconnected.
Go to TORQUE CONVERTER CLUTCH SOLENOID
VALVE, AT-74.
t1= 2.5 seconds t2= 2.0 seconds t3= 1.0 second
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Self-diagnosis (Cont'd)
AT-17
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SPORT indicator lamps
8th judgement flicker is longer than others.
SAT801H
A/T fluid temperature sensor is disconnected or TCM power
source circuit is damaged.
Go to A/T FLUID TEMPERATURE SENSOR AND TCM
POWER SOURCE, AT-78.
Flickers as shown below.
SAT804H
Battery power is low.
Battery has been disconnected for a long time.
Battery is connected conversely.
(When reconnecting TCM connectors. Ð This is not a prob-
lem.)
9th judgement flicker is longer than others.
SAT802H
Engine speed signal circuit is short-circuited or disconnected.
Go to ENGINE SPEED SIGNAL, AT-82.
Does not come on.
SAT805H
Park/neutral position, overdrive control or throttle (accelera-
tor) position switches circuit is disconnected or TCM is dam-
aged.
Go to PARK/NEUTRAL POSITION, OVERDRIVE CON-
TROL AND THROTTLE (ACCELERATOR) POSITION
SWITCHES, AT-93.
10th judgement flicker is longer than others.
SAT803H
Line pressure solenoid valve circuit is short-circuited or dis-
connected.
Go to LINE PRESSURE SOLENOID VALVE, AT-86.
t4= 1.0 second
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Self-diagnosis (Cont'd)
AT-18
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Diagnosis by CONSULT-II
NOTICE
1. The CONSULT-II electrically displays shift timing and lock-up timing (that is, operation timing of eachsolenoid).
Check for time difference between actual shift timing and the CONSULT-II display. If the difference is
noticeable, mechanical parts (except solenoids, sensors, etc.) may be malfunctioning. Check mechanical
parts using applicable diagnostic procedures.
2. Shift schedule (which implies gear position) displayed on CONSULT-II and that indicated in Service Manual may differ slightly. This occurs because of the following reasons:
IActual shift schedule has more or less tolerance or allowance,
I Shift schedule indicated in Service Manual refers to the point where shifts start. Gear position displayed
on CONSULT-II indicates the point where shifts are completed.
3. Shift solenoid valve ªAº or ªBº is displayed on CONSULT-II at the start of shifting. Gear position is displayed upon completion of shifting (which is computed by TCM).
4. Additional CONSULT-II information can be found in the Operation Manual supplied with the CONSULT-II unit.
SELF-DIAGNOSTIC RESULT TEST MODE
Refer to AT-14.
DATA MONITOR DIAGNOSTIC TEST MODE
Item DisplayMonitor item
Description Remarks
ECU
input
signals Main
signals
Vehicle speed sensor 1
(A/T)
(Revolution sensor) VHCL/S SE×A/T
[km/h] or [mph]
XÐI
Vehicle speed computed from signal
of revolution sensor is displayed. When racing engine in ªNº or ªPº posi-
tion with vehicle stationary, CON-
SULT-II data may not indicate
0 km/h (0 MPH).
Vehicle speed sensor 2
(Meter) VHCL/S SE×MTR
[km/h] or [mph]
XÐI
Vehicle speed computed from signal
of vehicle speed sensor is dis-
played. Vehicle speed display may not be
accurate under approx. 10 km/h
(6 MPH). It may not indicate 0 km/h (0
MPH) when vehicle is stationary.
Throttle (accelerator)
position sensor THRTL POS SEN
[V]
XÐI
Throttle (accelerator) position sen-
sor signal voltage is displayed.
A/T fluid temperature
sensor FLUID TEMP SE
[V]
XÐI
A/T fluid temperature sensor signal
voltage is displayed.
I Signal voltage lowers as fluid tem-
perature rises.
Battery voltage BATTERY VOLT [V]XÐI
Source voltage of TCM is displayed.
Engine speed ENGINE SPEED [rpm]XXI
Engine speed, computed from
engine speed signal, is displayed. Engine speed display may not be
accurate under approx. 800 rpm. It
may not indicate 0 rpm even when
engine is not running.
Overdrive control switch OVERDRIVE SW [ON/OFF]XÐI
ON/OFF state computed from signal
of overdrive control SW is displayed.
P/N position switch P/N POSI SW [ON/OFF]XÐI
ON/OFF state computed from signal
of P/N position SW is displayed.
R position switch R POSITION SW [ON/OFF]XÐI
ON/OFF state computed from signal
of R position SW is displayed.
D position switch D POSITION SW [ON/OFF]XÐI
ON/OFF state computed from signal
of D position SW is displayed.
2 position switch 2 POSITION SW [ON/OFF]XÐI
ON/OFF status, computed from sig-
nal of 2 position SW, is displayed.
1 position switch 1 POSITION SW [ON/OFF]XÐI
ON/OFF status, computed from sig-
nal of 1 position SW, is displayed.
ASCD-cruise signal ASCD×CRUISE [ON/OFF]XÐI
Status of ASCD cruise signal is dis-
played.
ON ... Cruising state
OFF ... Normal running state I
This is displayed even when no
ASCD is mounted.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
AT-20
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Introduction
The TCM receives a signal from the vehicle-speed sensor, throttle
(accelerator) position sensor or park/neutral position switch and
provides shift control or lock-up control via solenoid valves.
Input and output signals must always be correct and stable in the
operation of the A/T system. The A/T system must be in good
operating condition and be free of valve seizure, solenoid valve
malfunction, etc.
It is much more difficult to diagnose an incident that occurs inter-
mittently rather than continuously. Most intermittent incidents are
caused by poor electric connections or improper wiring. In this
case, careful checking of suspected circuits may help prevent the
replacement of good parts.
A visual check only may not find the cause of the incidents. A road
test with CONSULT-II or a circuit tester connected should be per-
formed. Follow the ªWork Flowº. Refer to AT-26.
Before undertaking actual checks, take a few minutes to talk with
a customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such incidents, especially
intermittent ones. Find out what symptoms are present and under
what conditions they occur. A ªDiagnostic Worksheetº like the
example (AT-24) should be used.
Start your diagnosis by looking for ªconventionalº incidents first.
This will help troubleshoot driveability incidents on an electronically
controlled engine vehicle.
SAT631IA
SAT632I
SEF234G
TROUBLE DIAGNOSIS Ð Introduction
AT-22
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