coolant TOYOTA SUPRA 1995 Service User Guide

FUNCTION OF ECU
w Control of Shifting Timing
The ECM has programmed into its memory the optimum shift pattern for each shift lever position (D, 2, L
position) and driving mode (Normal or Manual).
Based on the appropriate shift pattern, the ECM turns No.1 and No.2 solenoid valves on or off in accor-
dance with the vehicle speed signal from the vehicle speed sensor and the throttle opening signal from the
throttle position sensor. In this manner, the ECM operates each shift valve, opening or closing the fluid pas-
sages to the clutches and brakes to permit up±shift or down±shift of the transmission.
HINT: The electronic control system provides shift timing and lock±up control only while the vehicle is travel-
ing forward. In REVERSE, PARK, and NEUTRAL, the transmission is mechanically, not electronically con-
trolled.
w Control of Overdrive
Driving in overdrive is possible if the O/D main switch is on and the shift lever is in the D position. However,
when the vehicle is being driven using the cruise control system (CCS), if the actual vehicle speed drops
to about 4 km/h (2 mph) below the set speed while the vehicle is running in overdrive, the CCS ECU sends
a signal to the ECM to release the overdrive and prevent the transmission from shifting back into overdrive
until the actual vehicle speed reaches the speed set in the CCS memory.
On this model, if the engine coolant temperature falls below 60°C (140°F), the ECM sends a signal to the
ECM, preventing the transmission from up±shifting into overdrive.
w Control of Lock±Up System
The ECM has programmed in its memory a lock±up clutch operation pattern for each driving mode (Normal
of Manual). Based on this lock±up pattern, the ECM turns lock±up solenoid valve on or off in accordance
with the vehicle speed signals received from the vehicle speed sensor and the throttle opening signals from
the throttle position sensor.
Depending on whether lock±up solenoid valve is on or off, the lock±up relay valve performs changeover
of the fluid passages for the converter pressure acting on the torque converter clutch to engage or disen-
gage the lock±up clutch.
Mandatory Cancellation of Lock±Up System:
If any of the following conditions exist, the ECM turns off lock±up solenoid valve to disengage the lock±up
clutch.
1) The brake light switch comes on (during braking).
2) The IDL points of the throttle position sensor close (throttle valve fully closed).
3) The vehicle speed drops 4 km/h (2 mph) or more below the set speed while the cruise control system
is operating.
4) The engine coolant temperature falls below 60°C (140°F) and vehicle speed is under 60 km/h (37
mph), or 35°C (95°F) and vehicle speed is under 40 km/h (25 mph).
The purpose of 1) and 2) above is to prevent the engine from stalling if the rear wheels lock up.
The purpose of 3) is to cause the torque converter clutch to operate to obtain torque multiplication. The
purpose of 4) is both to improve general driveability, and to speed up transmission warm±up.
Also, while the lock±up system is in operation, the ECM will temporarily turn it off during up±shift or down±
shift in order to decrease shifting shock. AT1±8
± AT340E (2JZ±GE) AUTOMATIC TRANSMISSIONOPERATION

 
 
 
8
 
 
 
No.1 and No.2 Vehicle Speed Sensor
 
 
 
Detects the vehicle speed. Ordinarily, transmission control
uses signals from the No.2 vehicle speed sensor, and the
No.1 vehicle speed sensor is used as a back±up.
 9Engine Coolant Temp SensorDetects the engine coolant temp 9Engine Coolant Temp. SensorDetects the engine coolant temp.
 
10ECMControls the engine and transmission actuators based on 10ECMControls the engine and transmission actuators based on
signals from each sensor. 
 11No 1 and No 2 Solenoid ValvesControl the hydraulic pressure applied to each shift valve,
 11No.1 and No.2 Solenoid ValvesControl the hydraulic ressure a lied to each shift valve,
and control the gear position and timing.
 
12
Lock±up Solenoid Valve
(For lock up control pressure modulaControls the hydraulic pressure applied to the lock±up 
 
12(For lock±up control pressure modula-
tion)Controls the hydraulic ressure a lied to the lock u
clutch and controls lock±up timing.
 
13O/D OFF Indicator Light
Blinks and warns the driver, while the O/D main switch is
pushed in when the electronic control circuit is malfunction 
 
13O/D OFF Indicator Lightpushed in, when the electronic control circuit is malfunction-
ing.
 
14Kick down SwitchDetects if the accelerator pedal is depressed beyond the 14Kick±down SwitchDetects if the accelerator edal is de ressed beyond the
full throttle valve opening position.
 
15A/T Fluid Temp SensorDetects the A/T fluid temp 15A/T Fluid Temp. SensorDetects the A/T fluid temp.
± AT340E (2JZ±GE) AUTOMATIC TRANSMISSIONOPERATIONAT1±11

PROBLEM SYMPTOM CONFIRMATION
Taking into consideration the results of the customer problem analysis, try to reproduce the symptoms of
the trouble. If the problem is that the transmission does not up±shift, does not down±shift, or the shift point
is too high or too low, conduct the following road test to confirm the automatic shift schedule and simulate
the problem symptoms.
ROAD TEST
NOTICE: Do the test at normal A/T fluid operating temp.
50±80°C (122 ± 176°F).
1. D POSITION TEST (NORM PATTERN)
Shift into the D position and keep the accelerator pedal
constant at the full throttle valve opening position, and check
the following points:
(a) Check up±shift operation.
Check that 1±2, 2±3 and 3±O/D up±shift takes place, at the
shift point shown in the automatic shift schedule.
(See page AT1±96)
HINT:
(1) O/D Gear Up±shift Prohibition Control.
w Coolant temp. is 60°C (140°F) or less.
w If there is a 10 km/h (6 mph) difference between the set
cruise control speed and
wvehicle speed.
wO/D main switch is pushed ON.
w(During O/D OFF, indicator light lights up.)
(2) O/D Gear Lock±up Prohibition Control.
w Brake pedal is depressed.
w Coolant temp. is 60°C (140°F) or less.
(b) Check for shift shock and slip.
Check for shock and slip at the 1±2, 2±3 and 3±O/ D up±
shifts.
(c) Check for abnormal noise and vibration.
Run at the D position lock±up or O/D gear and check for ab-
normal noise and vibration.
HINT: The check for the cause of abnormal noise and vibra-
tion must be performed very thoroughly as it could also be
due to loss of balance in the torque converter clutch, etc.
± AT340E (2JZ±GE) AUTOMATIC TRANSMISSIONTROUBLESHOOTINGAT1±37

(d). Check kick±down operation.
While running in the D position, 2nd, 3rd and O/D gears,
check to see that the possible kick±down vehicle speed limits
for 2 " 1, 3 " 2 and O/D " 3 kick±downs conform to those
indicated on the automatic shift schedule. (See page
AT1±96)
(e) Check for abnormal shock and slip at kick±down.
(f) Check the lock±up mechanism.
(1) Drive in D position, O/D gear, at a steady speed (lock±up
ON) of about 61 km/h (38 mph).
(2) Lightly depress the accelerator pedal and check that the
RPM does not change abruptly.
If there is a big jump in RPM, there is no lock±up.
2. D POSITION TEST (MANU PATTERN)
Shift into the D position and hold the accelerator pedal
constant at the full throttle valve opening position, and check
the following points:
(a) Check up±shift operation.
2±3 and 3±O/D up shifts should take place, and shift points
should conform to those shown in the automatic shift sched-
ule.
(See page AT1±96)
HINT:
w O/D up±shift or lock±up will not occur when the engine
coolant temp. is below 605C (1405F) and speed is under
63 km/h (39 mph), or if there is a 10 km/h (6 mph)
difference between the set cruise control speed.
w 3rd up±shift or lock±up will not occur when engine
coolant temp. is 355C (955F) and speed is under 40 km/h
(25 mph).
(b) Check for shift shock and slip.
In the same manner, check the shock slip at the 2 " 3 and
3 " O/D up±shifts. AT1±38
± AT340E (2JZ±GE) AUTOMATIC TRANSMISSIONTROUBLESHOOTING

AT1±83AT1±85AT1±88AT1±91AT1±64EG±312AT1±56AT1±60AT1±62
Stop light switch
circuitPattern select switch
circuitO/D switch O/D OFF
indicator light circuitECMA/T fluid temp.
sensor circuitO/D cancel signal
circuitEngine coolant
temp. switch circuitOFF±Vehicle repairmatrix chartOn±Vehicle repairmatrix chart
± AT340E (2JZ±GE) AUTOMATIC TRANSMISSIONTROUBLESHOOTINGAT1±59

LOCK±UP POINT
NORM Mode
 
 
D position km/h (mph)
Throttle valve opening 5% 
 Lock±up ON
 
 Lock±up OFF
 3rd Gear (O/D switch OFF) 56±62 (35±39) 53±59 (35±39)
 O/D Gear 56±62 (35±39) 53±59 (35±39)
MANU Mode
 
 D position km/h (mph)
Throttle valve opening 5%
 
 Lock±up ON
 
 Lock±up OFF
 
 3rd Gear (O/D switch OFF)
 
 98±105 (61±65)
 
 92±99 (57±62)
 O/D Gear 163±175 (101±109) 56±62 (35±39)
HINT:
(1) There is no lock±up in the 2 and L positions.
(2) In the following cases, the lock±up will be released regardless of the lock±up pattern.
w When the throttle valve is completely closed.
w When the brake light switch is ON.
(3) Shift up to 3rd will not occur when the engine coolant temp. is below 35°C (95°F) and the vehicle
speed is below 40 km/h (25 mph).
(4) Shift±up to O/D will not occur when the engine coolant temp. is below 60°C (140°F) and the vehicle
speed is below 63 km/h (39 mph)
(5) When the vehicle speed drops to 10 km/h (6 mph) or more below the cruise control set vehicle speed,
shift down from O/D to 3rd occurs.
± AT340E (2JZ±GE) AUTOMATIC TRANSMISSIONSERVICE SPECIFICATIONSAT1±97

ELECTRONIC CONTROL SYSTEM
The electronic control system for the A340E automatic transmission provides extremely precise control of
the gear shift timing and lock±up timing in response to driving conditions as sensed by various sensors
located throughout the vehicle and in response to the engine's running condition.
At the same time, the ECM control reduces vehicle squat when the vehicle starts out and gear shift shock.
The electronic control system is also equipped with a self diagnosis system which diagnoses malfunctions
for the vehicle to continue functioning when a malfunction occurs.
CONSTRUCTION
The electronic control system can be broadly divided onto three groups; the sensors, ECM and actuators.
No. 1 Vehicle Speed Sensor
No. 2 Vehicle Speed Sensor
Crankshaft Position Sensor
Camshaft Position Sensor No.1, No.2
Park/Neutral Position Switch

Neutral Start Signal

Shift lever Position Signal

Idling Signal

Throttle Position Signal
Main (Sub) Ð throttle Position Sensor
Engine Coolant temp. Sensor
A/T Fluid Temp. Sensor
O/D Main Switch
Cruise Control ECU
Kick±Down Switch
Stop Light Switch
Pattern Select Switch
SENSORSECMACTUATORS
No.1 Solenoid Valve
No.2 Solenoid Valve
No.3 Solenoid Valve
No.4 Solenoid Valve
No.5 Solenoid Valve
Engine Torque Control (ESA)
Igniters
Ignition Coils
Distributors
Spark Plugs
O/D OFF Indicator Light
(Diagnostic Trouble Code
Display)
TRAC ECU
O/D Direct Clutch Speed Sensor
± A340E (2JZÐGTE) AUTOMATIC TRANSMISSIONOPERATIONAT2±7

 O/D Direct Clutch Speed Sensor Detects the input shaft speed from 1st gear to 3rd gear
 Engine Coolant Temp. Sensor Detects the engine coolant temp.
 
 ECM 
 
Controls the engine and transmission actuators based on signals from
each sensor.
 
 No.1 and No.2 Solenoid Valves 
 
Control the hydraulic pressure applied to each shift valve, and control the
gear position and timing.
 
 
 
No.4 Solenoid Valve
(For accumulator back pressure modulation) 
 
 
Controls the hydraulic pressure applied to the back chamber of the accu-
mulator and smoothes the engagement of clutches and brakes during
shifting.
 
 
No.3 Solenoid Valve
(For lock±up control pressure modulation) 
 
Controls the hydraulic pressure applied to the lock±up clutch and controls
lock±up timing.
 
 
No.5 Solenoid Valve
(For line pressure modulation) 
 Controls the line pressure.
 
 O/D OFF Indicator Light 
 
Blinks and warns the driver, while the O/D main switch is pushed in,
when the electronic control circuit is malfunctioning.
 A/T Fluid Temp. Sensor Detects A/T fluid temp.
± A340E (2JZÐGTE) AUTOMATIC TRANSMISSIONOPERATIONAT2±11

PROBLEM SYMPTOM CONFIRMATION
Taking into consideration the results of the customer problem analysis, try to reproduce the symptoms of
the trouble. If the problem is that the transmission does not up±shift, does not down±shift, or the shift point
is too high or too low, conduct the following road test to confirm the automatic shift schedule and simulate
the problem symptoms.
ROAD TEST
NOTICE: Do the test at normal A/T fluid operating temp.
50±805C (122±1765F).
1. D POSITION TEST (NORM PATTERN)
Shift into the D position and keep the accelerator pedal
constant at the full throttle valve opening position, and check
the following points:
(a) Check up±shift operation.
Check that 1±2, 2±3 and 3±O/D up±shift takes place, at the
shift point shown in the automatic shift schedule.
(See page AT2±116)
HINT:
(1) O/D Gear Up±shift Prohibition Control.
wCoolant temp. is 605C (1405F) or less.
wIf there is a 10 km/h (6 mph) difference between the set
cruise control speed and vehicle speed.
wO/D main switch is pushed ON.
`(During O/D OFF, indicator light lights up.)
(2) O/D Gear Lock±up Prohibition Control.
wBrake pedal is depressed.
wCoolant temp. is 605C (1405F) or less.
(b) Check for shift shock and slip.
Check for shock and slip at the 1±2, 2±3, and 3±O/ D up±
shifts.
(c) Check for abnormal noise and vibration.
Run at the D position lock±up or O/D gear and check for ab-
normal noise and vibration.
HINT: The check for the cause of abnormal noise and vibra-
tion must be performed very thoroughly as it could also be
due to loss of balance in the, torque converter clutch, etc.
± A340E (2JZÐGTE) AUTOMATIC TRANSMISSIONTROUBLESHOOTINGAT2±37

(d) Check kick±down operation.
While running in the D position, 2nd, 3rd and O/D gears,
check to see that the possible kick±down vehicle speed limits
for 2
" 1, 3 " 2 and O/D " 3 kick±downs conform to those
indicated on the automatic shift schedule.
(See page AT2±116)
(e) Check for abnormal shock and slip at kick±down.
(f) Check the lock±up mechanism.
(1) Drive in D position, O/D gear, at a steady speed (lock±up
ON) of about 59 km/h (37 mph).
(2) Lightly depress the accelerator pedal and check that the
RPM does not change abruptly.
If there is a big jump in RPM, there is no lock±up.
2. D POSITION TEST (MANU PATTERN)
Shift into the D position and hold the accelerator pedal
constant at the full throttle valve opening position, and check
the following points:
(a) Check up±shift operation.
2±3 and 3±O/D up shifts should take place, and shift points
should conform to those shown in the automatic shift sched-
ule.
(See page AT2±116)
HINT:
wO/D up±shift or lock±up will not occur when the engine
coolant temp. is below 605C (1405F) and speed is under
60 km/h (37 mph), or if there is a 10 km/h (6 mph)
difference between the set cruise control speed.
w3rd up±shift or lock±up will not occur when engine
coolant temp. is 355C (955F) and speed is under 40 km/h
(25 mph).
(b) Check for shift shock and slip.
In the same manner, check the shock slip at the 2
" 3 and
3
" O/D up±shifts. AT2±38
± A340E (2JZÐGTE) AUTOMATIC TRANSMISSIONTROUBLESHOOTING