1995 TOYOTA SUPRA coolant temperature

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

TROUBLESHOOTING
The table below will be useful for you in troubleshooting these electrical problems. The most likely causes
of the malfunction are shown in the order of their probability. Inspect each part in the order shown, and
replace the part when it is found to be faulty.
METER, GAUGES AND ILLUMINATION
 Trouble Parts name (See page)
 
 
 
Tachometer, Fuel Gauge and Engine Coolant Tempera-
ture Gauge do not operate
 
 
 
1. GAUGE Fuse (BE±6)
2. Meter Circuit Plate (BE±44)
3. Wire Harness
 
 
 
Speedometer does not operate
 
 
 
1. Vehicle Speed Sensor (BE±46)
2. Meter Circuit Plate (BE±44)
3. Wire Harness
 
 
 
 
Tachometer does not operate
 
 
 
 
1. Igniter
2. ECM (EG Section)
3. Meter Circuit Plate (BE±44)
4. Wire Harness
 
 
 
 
Fuel Gauge does not operate or abnormal operation
 
 
 
 
1. Fuel Receiver Gauge (BE±48)
2. Fuel Sender Gauge (BE±49)
3. Meter Circuit Plate (BE±44)
4. Wire Harness
 
 
 
 
Engine Coolant Temperature Gauge does not operate or
abnormal operation
 
 
 
 
1. Engine Coolant Temperature Receiver Gauge (BE±50)
2. Engine Coolant Temperature Sender Gauge (BE±50)
3. Meter Circuit Plate (BE±44)
4. Wire Harness
 
 
 
 
All illumination lights do not light up
 
 
 
 
1. TAIL Fuse (BE±6)
2. Light Control Rheostat (BE±54)
3. Meter Circuit Plate (BE±44)
4. Wire Harness
 
 
Only one illumination light does not light up 
 
1. Bulb
2. Meter Circuit Plate (BE±44)
± BODY ELECTRICAL SYSTEMCOMBINATION METERBE±41

ENGINE COOLANT TEMPERATURE
GAUGE INSPECTION
1. INSPECT RECEIVER GAUGE OPERATION
(a) Disconnect the connector from the sender gauge.
(b) Turn the ignition switch ON, check that the receiver gauge
needle indicates COOL.
(c) Ground terminal on the wire harness side connector through
a 3 W test bulb.
(d) Turn the ignition switch ON, check that the bulb lights up and
the receiver gauge needle moves toward the hot side.
If operation is as specified, replace the sender gauge.
Then recheck the system.
If operation is not as specified, measure the receiver gauge
resistance.
2. INSPECT RECEIVER GAUGE RESISTANCE
Measure the resistance between terminals.
HINT: Connect the test leads so that the current from the
ohmmeter can flow according to the chart order.
 Between terminals Resistance (
) 
A±B 
Approx. 229.7
 A±C Approx. 54.0
 B±C Approx. 175.7
If resistance value is not as specified, replace the engine
coolant temperature receiver gauge.
3. INSPECT SENDER GAUGE RESISTANCE
Measure the resistance between terminal and gauge body.
 Temperature °C (°F) Resistance (
)
 50 (122.0) 160 ~ 240
 120 (248.0) 17.1 ~ 21.2
If resistance value is not as specified, replace the engine
coolant temperature sender gauge. BE±50
± BODY ELECTRICAL SYSTEMCOMBINATION METER

  TACHOMETER (ON±VEHICLE) 
 Standard indication (rpm) Allowable range (rpm)
 700 630 ± 770
 1000 915 ± 1115
 2000 1920 ± 2220
 3000 2890 ± 3350
 4000 3940 ± 4400
50005025 ± 5425 
6500
 
6650 ± 6950 
7000
 
7025 ± 7625  OD/TRIP METER (CONNECTOR CONNECTED) 
  1 ± Ground (Ignition SW position ON) Battery positive voltage  4 ± Ground (Light Control SW position TAIL or HEAD) Battery positive voltage  5 ± 7 (Ignition SW ON and drive the vehicle slowly) OV eBattery positive voltage  6 ± 7 (Ignition SW ON and drive the vehicle slowly) OV emore than 5V  8 ± Ground (Constant) Battery positive voltage 
 
 
10 ± Ground (Ignition SW ON, Light Control SW TAIL or
HEAD and turn the Light Control Rheostat
knob to clockwise) 
 
 6V " 0V
  FUEL RECEIVER GAUGE 
 A ± B Approx. 269.7

 A ± C Approx. 123.5

 B ± C Approx. 146.2

  FUEL SENDER GAUGE 
  Float position: F Approx. 4.0

  Float position: 1/2 Approx. 55.0

  Float position: E Approx. 107.0

  ENGINE COOLANT TEMPERATURE RECEIVER GAUGE 
 A ± B Approx. 229.7

 A ± C Approx. 54.0

 B ± C Approx. 175.7

  ENGINE COOLANT TEMPERATURE SENDER GAUGE 
  50 °C (122.0 °F) 160 ± 240

  120 °C (248.0 °F) 17.1 ± 21.2

  LIGHT FAILURE SENSOR 
  3 ± Ground (Light Control SW position OFF) No voltage
  3 ± Ground (Light Control SW position TAIL or HEAD) Battery positive voltage
  4 ± Ground (Ignition SW position LOCK or ACC) No voltage
  4 ± Ground (Ignition SW position ON) Battery positive voltage
  7 ± Ground (Stop Light SW position OFF) No voltage
  7 ± Ground (Stop Light SW position ON) Battery positive voltage
 8 ± Ground (Engine stop)No voltage 
8 ± Ground (Engine running)
 
Battery positive voltage 
INTEGRATION RELAY (Seat Belt Warning)
 
  1 ± Ground (Constant) Battery positive voltage  9 ± Ground (Ignition SW LOCK or ACC) No voltage  9 ± Ground (Ignition SW ON) Battery positive voltage
BE±202± BODY ELECTRICAL SYSTEMSERVICE SPECIFICATIONS

THERMOSTAT REMOVAL
HINT: Removal of the thermostat would have an adverse ef-
fect, causing a lowering of cooling efficiency.
Do not remove the thermostat, even if the engine tends to
overheat.
1. 2JZ±GTE:
REMOVE ENGINE UNDER COVER
2. DRAIN ENGINE COOLANT
3. 2JZ±GE:
DISCONNECT WATER INLET FROM WATER PUMP, AND
REMOVE THERMOSTAT
(a) Remove the 2 nuts holding the water inlet to the water pump,
and disconnect the water inlet from the water pump.
(b) Remove the thermostat.
(c) Remove the gasket from the thermostat.
4. 2JZ±GTE:
REMOVE WATER INLET, LOWER RADIATOR HOSE AS-
SEMBLY AND THERMOSTAT
(a) Disconnect the lower radiator hose from the radiator.
(b) Remove the 2 nuts holding the water inlet to the water pump,
and disconnect the water inlet and lower radiator hose from
the water pump.
(c) Remove the thermostat.
(d) Remove the gasket from the thermostat.
THERMOSTAT INSPECTION
INSPECT THERMOSTAT
HINT: The thermostat is numbered with the valve opening
temperature.
(a) Immerse the thermostat in water and gradually heat the
water.
(b) Check the valve opening temperature.
Valve opening temperature:
80±84°C (176±183°F)
If the valve opening temperature is not as specified, replace
the thermostat.
± ENGINECOOLING SYSTEMEG±341

10. REMOVE RADIATOR ASSEMBLY
(a) 2JZ±GTE:
Disconnect the ECT switch (for electric cooling fan connec-
tor) and wire harness.
(b) 2JZ±GTE:
Disconnect the electric cooling fan connector and wire har-
ness.
(c) Remove the bolt and upper radiator support. Remove the 2
upper radiator supports.
INSTALLATION HINT: After installation, check that the rub-
ber cushion (A) of the support is not depressed.
Torque: 15 NVm (155 kgfVcm, 11 ftVlbf)
(d) Lift out the radiator assembly.
(e) Remove the 2 lower radiator supports.
11. REMOVE DRAIN HOSE FROM RADIATOR
12. 2JZ±GTE:
REMOVE ENGINE COOLANT TEMPERATURE (ECT)
SWITCH FROM RADIATOR
(a) Remove the ECT switch.
INSTALLATION HINT: Apply soapy water to the O±ring, and
install the ECT switch.
Torque: 7.4 NVm (75 kgfVcm, 65 in.Vlbf)
(b) Remove the O±ring from the ECT switch.
INSTALLATION HINT: Use a new O±ring.
13. 2JZ±GTE:
REMOVE ELECTRIC COOLING FAN FROM RADIATOR
Remove the 3 bolts and cooling fan.
14. REMOVE NO.1 FAN SHROUD FROM RADIATOR
Remove the 4 bolts and No.1 fan shroud.
± ENGINECOOLING SYSTEMEG±347

ELECTRIC COOLING FAN (2JZ±GTE)
On±Vehicle Inspection
1. C H E C K C O O L I N G FA N O P E R AT I O N W I T H L O W
TEMPERATURE (Below 88°C (190°F))
(a) Turn the ignition switch ON.
(b) Check that the cooling fan stops.
If not, check the cooling fan relay and ECT switch, and check
for a separated connector or severed wire between the No.1
radiator fan relay and ECT switch.
(c) Disconnect the ECT switch connector.
(d) Check that the cooling fan rotates.
If not, check the No.1 radiator relay, No.2 radiator fan relay,
cooling fan, fuses, and check for short circuit between the
No.1 radiator fan relay and ECT switch.
(e) Reconnect the ECT switch connector.
2. CHECK COOLING FAN OPERATION WITH HIGH
TEMPERATURE (Above 97°C (207°F))
(a) Start the engine, and raise coolant temperature to above
97°C (207°F).
(b) Check that the cooling fan rotates.
If not, replace the ECT switch.
± ENGINECOOLING SYSTEMEG±353

Engine Coolant Temperature (ECT)
Switch
ECT SWITCH INSPECTION
1. REMOVE ENGINE UNDER COVER
2. DRAIN ENGINE COOLANT
3. REMOVE ECT SWITCH
(a) Disconnect the ECT switch connector.
(b) Remove the ECT switch.
(c) Remove the O±ring from the ECT switch.
4. INSPECT ECT SWITCH
(a) Usin g an oh mme te r, ch e ck th a t th e re is no co n tin u ity
between the terminals when the coolant temperature is
above 97°C (207°F).
(b) Using an ohmmeter, check that there is continuity between
the terminals when the coolant temperature is below 88°C
(190°F).
If continuity is not as specified, replace the switch.
5. REINSTALL ECT SWITCH
(a) Install a new O±ring to the ECT switch.
(b) Apply soapy water to the O±ring.
(c) Install the ECT switch.
Torque: 7.4 NVm (75 kgfVcm, 65 in.Vlbf)
(d) Connect the ECT switch connector.
6. REFILL WITH ENGINE COOLANT
7. START ENGINE AND CHECK FOR LEAKS
8. REINSTALL ENGINE UNDER COVER
No.1 Radiator Fan Relay
(ºRADIATOR FAN RELAYº)
RADIATOR FAN RELAY INSPECTION
1. w/ Auto Spoiler:
REMOVE LH HEADLIGHT
2. w/o Auto Spoiler:
REMOVE ENGINE UNDER COVER
3. REMOVE RADIATOR FAN RELAY
4. INSPECT RADIATOR FAN RELAY
A. Inspect relay continuity
(a) Using an ohmmeter, check that there is continuity between
terminals 3 and 4.
(b) Check that there is no continuity between terminals 1 and 2.
If continuity is as specified, replace the relay. EG±356
± ENGINECOOLING SYSTEM