A/T CONTROL SYSTEM
AT-17
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CLUTCH AND BAND CHART
l—Operates
l—Operates during “progressive” acceleration.
l—Operates and effects power transmission while coasting.
l—Line pressure is applied but does not affect power transmission.
l—Operates under conditions shown in HLR/C Operating Condition
l—Operates under conditions shown in LC/B Operating Condition. Delay control is applied during “D” (4,3,2,1)“N” shift.
l*1: A/T will not shift to 5th when overdrive control switch is set in OFF position.Shift position I/C HLR/C D/C R/B FR/B LC/B Fwd/B1st
OWCFwd
OWC3rd
OWCRemarks
PPARK POSITION
RREVERSE POSI-
TION
NNEUTRAL POSI-
TION
D*11st
Automatic shift
1Û2Û3Û4Û5 2nd
3rd
4th
5th
31st
Automatic shift
1Û2Û3Ü4 2nd
3rd
4th
21st
Automatic shift
1Û2Ü3Ü4 2nd
3rd
4th
11st
Locks (held sta-
tionary in 1st
gear)
1Ü2Ü3Ü4 2nd
3rd
4th
SCIA5642E
A/T CONTROL SYSTEM
AT-27
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TCM FunctionECS00FWI
The function of the TCM is to:
lReceive input signals sent from various switches and sensors.
lDetermine required line pressure, shifting point, lock-up operation, and engine brake operation.
lSend required output signals to the respective solenoids.
CONTROL SYSTEM OUTLINE
The A/T senses vehicle operating conditions through various sensors or signals. It always controls the opti-
mum shift position and reduces shifting and lock-up shocks.
CONTROL SYSTEM DIAGRAM
SENSORS (or SIGNALS)
TCM
ACTUATORS
PNP switch
Accelerator pedal position signal
Closed throttle position signal
Wide open throttle position signal
Engine speed signal
A/T fluid temperature sensor
Revolution sensor
Vehicle speed signal
1st position switch signal
Overdrive control switch signal
Stop lamp switch signal
Turbine revolution sensor
ATF pressure switchShift control
Line pressure control
Lock-up control
Engine brake control
Timing control
Fail-safe control
Self-diagnosis
CONSULT-II communication line
Duet-EA control
CAN systemInput clutch solenoid valve
Direct clutch solenoid valve
Front brake solenoid valve
High and low reverse clutch solenoid
valve
Low coast brake solenoid valve
Torque converter clutch solenoid valve
Line pressure solenoid valve
OD OFF indicator lamp
Starter relay
Back-up lamp relay
SCIA7332E
AT-28
A/T CONTROL SYSTEM
CAN Communication
ECS00FWJ
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only. For details, refer toLAN-30,
"CAN Communication Unit".
Input/Output Signal of TCMECS00FWK
*1: Spare for vehicle speed sensor·A/T (revolution sensor)
*2: Spare for accelerator pedal position signal
*3: If these input and output signals are different, the TCM triggers the fail-safe function.
*4: Used as a condition for starting self-diagnosis; if self-diagnosis are not started, it is judged that there is some kind of error.
*5: Input by CAN communications.
*6: Output by CAN communications.Control itemLine
pressure
controlVehicle
speed
controlShift
controlLock-up
controlEngine
brake
controlFail-safe
function
(*3)Self-diag-
nostics
function
InputAccelerator pedal position signal
(*5)XXXXXX X
Vehicle speed sensor A/T
(revolution sensor)XXXXXX X
Vehicle speed sensor MTR
(*1) (*5)X
Closed throttle position signal
(*5)X(*2) X X X X(*4)
Wide open throttle position signal
(*5)XX(*4)
Turbine revolution sensor 1 X X X X X
Turbine revolution sensor 2
(for 4th speed only)XXXXX
Engine speed signals
(*5)XXXXXX X
Stop lamp switch signal
(*5)XXX X(*4)
A/T fluid temperature sensors 1, 2 X X X X X X
ASCDOperation signal
(*5)XXX
Overdrive cancel signal
(*5)X
OutputDirect clutch solenoid
(ATF pressure switch 5)XX X X
Input clutch solenoid
(ATF pressure switch 3)XX X X
High and low reverse clutch solenoid
(ATF pressure switch 6)XX X X
Front brake solenoid
(ATF pressure switch 1)XX X X
Low coast brake solenoid
(ATF pressure switch 2)XX XX X
Line pressure solenoid X X X X X X X
TCC solenoid X X X
Self-diagnosis table
(*6)X
Starter relayXX
A/T CONTROL SYSTEM
AT-31
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SHIFT CHANGE
The clutch is controlled with the optimum timing and oil pressure by the engine speed, engine torque informa-
tion, etc.
Shift Change System Diagram
*1: Full phase real-time feedback control monitors movement of gear ratio at gear change, and controls oil
pressure at real-time to achieve the best gear ratio.
Lock-up ControlECS00FWN
The torque converter clutch piston in the torque converter is engaged to eliminate torque converter slip to
increase power transmission efficiency.
The torque converter clutch control valve operation is controlled by the torque converter clutch solenoid valve,
which is controlled by a signal from TCM, and the torque converter clutch control valve engages or releases
the torque converter clutch piston.
Lock-up Operation Condition Table
TORQUE CONVERTER CLUTCH CONTROL VALVE CONTROL
Lock-up Control System Diagram
Lock-up Released
In the lock-up released state, the torque converter clutch control valve is set into the unlocked state by the
torque converter clutch solenoid and the lock-up apply pressure is drained.
In this way, the torque converter clutch piston is not coupled.
PCIA0013E
selector lever “D” position “3” position “2” position
Gear position 5 4 3 2
Lock-up´–´´
PCIA0014E
AT-32
A/T CONTROL SYSTEM
Lock-up Applied
In the lock-up applied state, the torque converter clutch control valve is set into the locked state by the torque
converter clutch solenoid and lock-up apply pressure is generated.
In this way, the torque converter clutch piston is pressed and coupled.
SMOOTH LOCK-UP CONTROL
When shifting from the lock-up released state to the lock-up applied state, the current output to the torque con-
verter clutch solenoid is controlled with the TCM. In this way, when shifting to the lock-up applied state, the
torque converter clutch is temporarily set to the half-clutched state to reduce the shock.
Half-clutched State
The current output from the TCM to the torque converter clutch solenoid is varied to gradually increase the
torque converter clutch solenoid pressure.
In this way, the lock-up apply pressure gradually rises and while the torque converter clutch piston is put into
half-clutched status, the torque converter clutch piston operating pressure is increased and the coupling is
completed smoothly.
Engine Brake ControlECS00FWO
lThe forward one-way clutch transmits the drive force from the engine to the rear wheels. But the reverse
drive from the rear wheels is not transmitted to the engine because the one-way clutch is idling.
Therefore, the low coast brake solenoid is operated to prevent the forward one-way clutch from idling and
the engine brake is operated in the same manner as conventionally.
lThe operation of the low coast brake solenoid switches the low coast brake switching valve and controls
the coupling and releasing of the low coast brake.
The low coast brake reducing valve controls the low coast brake coupling force.
SCIA1520E
A/T CONTROL SYSTEM
AT-33
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Control ValveECS00FWP
FUNCTION OF CONTROL VALVE
FUNCTION OF PRESSURE SWITCH
Name Function
Torque converter regulator valveIn order to prevent the pressure supplied to the torque converter from being excessive, the
line pressure is adjusted to the optimum pressure (torque converter operating pressure).
Pressure regulator valve
Pressure regulator plug
Pressure regulator sleeveAdjusts the oil discharged from the oil pump to the optimum pressure (line pressure) for
the driving state.
Front brake control valveWhen the front brake is coupled, adjusts the line pressure to the optimum pressure (front
brake pressure) and supplies it to the front brake. (In 1st, 2nd, 3rd, and 5th gears, adjusts
theclutchpressure.)
Accumulator control valveAdjusts the pressure (accumulator control pressure) acting on the accumulator piston and
low coast reducing valve to the pressure appropriate to the driving state.
Pilot valve AAdjusts the line pressure and produces the constant pressure (pilot pressure) required for
line pressure control, shift change control, and lock-up control.
Pilot valve BAdjusts the line pressure and produces the constant pressure (pilot pressure) required for
shift change control.
Low coast brake switching valve During engine braking, supplies the line pressure to the low coast brake reducing valve.
Low coast brake reducing valveWhen the low coast brake is coupled, adjusts the line pressure to the optimum pressure
(low coast brake pressure) and supplies it to the low coast brake.
N-R accumulator Produces the stabilizing pressure for when N-R is selected.
Direct clutch piston switching valve Operates in 4th gear and switches the direct clutch coupling capacity.
High and low reverse clutch control valveWhen the high and low reverse clutch is coupled, adjusts the line pressure to the optimum
pressure (high and low reverse clutch pressure) and supplies it to the high and low reverse
clutch. (In 1st, 3rd, 4th and 5th gears, adjusts the clutch pressure.)
Input clutch control valveWhen the input clutch is coupled, adjusts the line pressure to the optimum pressure (input
clutch pressure) and supplies it to the input clutch. (In 4th and 5th gears, adjusts the clutch
pressure.)
Direct clutch control valveWhen the direct clutch is coupled, adjusts the line pressure to the optimum pressure
(direct clutch pressure) and supplies it to the direct clutch. (In 2nd, 3rd, and 4th gears,
adjusts the clutch pressure.)
TCC control valve
TCC control plug
TCC control sleeveSwitches the lock-up to operating or released. Also, by performing the lock-up operation
transiently, lock-up smoothly.
Torque converter lubrication valveOperates during lock-up to switch the torque converter, cooling, and lubrication system oil
path.
Cool bypass valve Allows excess oil to bypass cooler circuit without being fed into it.
Line pressure relief valve Discharges excess oil from line pressure circuit.
N-D accumulator Produces the stabilizing pressure for when N-D is selected.
Manual valveSends line pressure to each circuit according to the select position. The circuits to which
the line pressure is not sent drain.
Name Function
ATFpressureswitch1(FR/B)Detects any malfunction in the front brake hydraulic pressure. When it detects any malfunction,
it puts the system into fail-safe mode.
ATFpressureswitch2(LC/B)Detects any malfunction in the low coast brake hydraulic pressure. When it detects any mal-
function, it puts the system into fail-safe mode.
ATFpressureswitch3(I/C)Detects any malfunction in the input clutch hydraulic pressure. When it detects any malfunction,
it puts the system into fail-safe mode.
ATF pressure switch 5 (D/C)Detects any malfunction in the direct clutch hydraulic pressure. When it detects any malfunc-
tion, it puts the system into fail-safe mode.
ATF pressure switch 6 (HLR/C)Detects any malfunction in the high and low reverse clutch hydraulic pressure. When it detects
any malfunction, it puts the system into fail-safe mode.
TROUBLE DIAGNOSIS
AT-35
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A/T Interlock
lIf there is an A/T interlock judgment malfunction, the A/T is fixed in 2nd gear to make driving possible.
NOTE:
When the vehicle is driven fixed in 2nd gear, a turbine revolution sensor malfunction is displayed,
but this is not a turbine revolution sensor malfunction.
lWhen the coupling pattern below is detected, the fail-safe action corresponding to the pattern is per-
formed.
A/T INTERLOCK COUPLING PATTERN TABLE
l:NG X:OK
A/T 1st Engine Braking
When there is an A/T first gear engine brake judgment malfunction, the low coast brake solenoid is switched
OFF to avoid the engine brake operation.
Line Pressure Solenoid
The solenoid is switched OFF and the line pressure is set to the maximum hydraulic pressure to make driving
possible.
Torque Converter Clutch Solenoid
The solenoid is switched OFF to release the lock-up.
Low Coast Brake Solenoid
When a malfunction (electrical or functional) occurs, in order to make driving possible. If the solenoid is ON,
the A/T is held in 2nd gear. If the solenoid is OFF, the A/T is held in 4th gear. (Engine brake is not applied in
1st and 2nd gear.)
Input Clutch Solenoid
If a malfunction (electrical or functional) occurs with the solenoid either ON or OFF, the A/T is held in 4th gear
to make driving possible.
Direct Clutch Solenoid
If a malfunction (electrical or functional) occurs with the solenoid either ON or OFF, the A/T is held in 4th gear
to make driving possible.
Front Brake Solenoid
If a malfunction (electrical or functional) occurs with the solenoid ON, in order to make driving possible, the A/
T is held in 5th gear. If the solenoid is OFF, the A/T 4th gear.
High and Low Reverse Clutch Solenoid
If a malfunction (electrical or functional) occurs with the solenoid either ON or OFF, the A/T is held in 4th gear
to make driving possible.
Turbine Revolution Sensor 1 or 2
The control is the same as if there were no turbine revolution sensors, 5th gear is prohibited.
Gear positionATF pressure switch output
Fail-safe
functionClutch pressure output pattern after fail-safe func-
tion
SW3
(I/C)SW6
(HLR/C)SW5
(D/C)SW1
(FR/B)SW2
(LC/B)I/C HLR/C D/C FR/B LC/B L/U
A/T interlock
coupling pat-
tern3rd – X X –lHeld in
2nd gearOFF OFF ON OFF OFF OFF
4th – X X –lHeld in
2nd gearOFF OFF ON OFF OFF OFF
5th X X – XlHeld in
2nd gearOFF OFF ON OFF OFF OFF
AT-36
TROUBLE DIAGNOSIS
How to Perform Trouble Diagnosis for Quick and Accurate Repair
ECS00FWX
INTRODUCTION
The TCM receives a signal from the vehicle speed sensor, accelera-
tor pedal position sensor or PNP switch and provides shift control or
lock-up control via A/T 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 oper-
ating condition and be free of valve seizure, solenoid valve malfunc-
tion, etc.
It is much more difficult to diagnose a error that occurs intermittently
rather than continuously. Most intermittent errors are caused by poor
electric connections or improper wiring. In this case, careful check-
ing of suspected circuits may help prevent the replacement of good
parts.
A visual check only may not find the cause of the errors. A road test
with CONSULT-II or a circuit tester connected should be performed.
Follow theAT-37, "
WORK FLOW".
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 errors, especially
intermittent ones. Find out what symptoms are present and under
what conditions they occur. A “DIAGNOSTIC WORKSFEET” as
shown on the example (Refer toAT-38
) should be used.
Start your diagnosis by looking for “conventional” errors first. This will
help troubleshoot driveability errors on an electronically controlled
engine vehicle.
Also check related Service bulletins.
SAT631IB
SAT632I
SEF234G