TOYOTA SUPRA 1995 Service Repair Manual

2. INSECT RECEIVER GAUGE RESISTANCE
Measure the resistance between terminals.
 Between terminals Resistance (
)
 A±B Approx. 269.7
 A±C Approx. 123.5
 B±C Approx. 146.2
If resistance value is not as specified, replace the fuel receiv-
er gauge.
3. INSPECT SENDER GAUGE RESISTANCE
Measure the resistance between terminals 2 and 3 for each
float position.
 
 Float position mm (in.)
 
 Resistance (
)
 F Approx. 33.8 (1.33) Approx. 4.0
 1/2 Approx. 44.8 (1.76) Approx. 55.0
 E Approx. 141.1 (5.55) Approx. 107.0
If resistance value is not as specified, replace the sender
gauge.
FUEL LEVEL WARNING INSPECTION
1. INSPECT WARNING LIGHT
(a) Disconnect the connector from the sender gauge.
(b) Connect terminals 1 and 3 on the wire harness side
connector.
(c) Turn the ignition switch ON, check that the warning light lights
up.
If the warning light does not light up, test the bulb or inspect
wire harness.
2. INSPECT SWITCH
(a) Apply battery positive voltage between terminals 1 and 3
through a 3.4 W test bulb, check that the bulb lights up.
HINT: It will take a short time for the bulb to light up.
(b) Submerge the switch in fuel, check that the bulb goes out.
If operation is not as specified, replace the sender gauge.
± BODY ELECTRICAL SYSTEMCOMBINATION METERBE±49

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

LOW OIL PRESSURE WARNING
INSPECTION
1. INSPECT SWITCH
(a) Check that there is continuity between terminal and ground
with the engine stopped.
(b) Check that there is no continuity between terminal and
ground with the engine running.
HINT: Oil pressure should be over 29 kPa (0.3 kgf/ cm
2, 4.3
psi)
If operation is not as specified, replace the switch.
2. INSPECT WARNING LIGHT
(a) Disconnect the connector from the warning switch and
ground terminal on the wire harness side connector.
(b) Turn the ignition switch ON, check that the warning light lights
up.
If the warning light does not light up, test the bulb or inspect
wire harness.
ENGINE OIL LEVEL WARNING
INSPECTION
1. INSPECT SWITCH
(a) Check that there is continuity between terminal with the
switch in each position.
(b) Heat the switch to above 60°C (140°F) in an oil bath.
(c) Check that there is continuity between terminals with the
switch ON (float up).
(d) Check that there is no continuity between terminals with the
switch OFF (float down).
If operation is not as specified, replace the switch.
2. INSPECT WARNING LIGHT
(a) Disconnect the connector from the switch.
(b) Ground terminal 1 on the wire harness connector.
(c) Turn the ignition switch ON. Check that the warning light
lights up approximately 40 seconds later.
If the warning light does not light up, inspect bulb or wire har-
ness.
± BODY ELECTRICAL SYSTEMCOMBINATION METERBE±51

BRAKE FLUID LEVEL WARNING
INSPECTION
1. INSPECT SWITCH
(a) Remove the reservoir tank cap and strainer.
(b) Disconnect the connector.
(c) Check that there is no continuity between terminals with the
switch OFF (float up).
(d) Use syphon, etc. to take fluid out of the reservoir tank.
(e) Check that there is continuity between terminals with the
switch ON (float down).
(f) Pour the fluid back in the reservoir tank.
If operation is not as specified, replace the switch.
2. INSPECT WARNING LIGHT
(a) Disconnect the connector from the brake fluid warning
switch.
(b) Release the parking brake pedal.
(c) Connect terminals on the wire harness side of the level
warning switch connector.
(d) Start the engine, check that the warning light lights up.
If the warning light does not light up, test the bulb or wire har-
ness.
PARKING BRAKE WARNING
INSPECTION
1. INSPECT SWITCH
(a) Check that there is continuity between terminal and switch
body with the switch ON (switch pin released).
(b) Check that there is no continuity between terminal and switch
body with the switch OFF (switch pin pushed in).
If operation is not as specified, replace the switch or inspect
ground point.
2. INSPECT WARNING LIGHT
(a) Disconnect the connector from the parking brake switch and
the brake fluid warning switch.
(b) Ground terminal on the wire harness side connector.
(c) Start the engine, check that the warning light lights up.
If the warning light does not light up, test the bulb or inspect
wire harness. BE±52
± BODY ELECTRICAL SYSTEMCOMBINATION METER

LIGHT FAILURE SENSOR INSPECTION
1. INSPECT SENSOR CIRCUIT
Disconnect the connector from the sensor and inspect the
connector on the wire harness side, as shown.
 
 
 
Tester connection to
terminal number
 
 
 
Condition
 
 
 
Specified condition
 1±Ground Constant Continuity*
 2±Ground Constant Continuity*
 9±Ground Constant Continuity* 
 10±Ground
 
 Constant
 
 Continuity*
 11±Ground Constant Continuity
 12±Ground Constant Continuity*
 3±Ground Light control switch position OFF No Voltage 3±Ground Light control switch position TAIL or HEAD Battery positive voltage 
 4±Ground
 
 Ignition switch position LOCK or ACC
 
 No voltage
 4±Ground Ignition switch position ON Battery positive voltage
 7±Ground Stop light switch position OFF No voltage
 7±Ground Stop light switch position ON Battery positive voltage 
 8±Ground
 
 Engine condition Stop
 
 No voltage
 8±Ground Engine condition Running Battery positive voltage
*: There is resistance because this circuit is grounded
through the bulb.
If circuit is as specified, replace the sensor.
If the circuit is not as specified, inspect the circuits connected
to other parts.
2. INSPECT WARNING LIGHT
(a) Disconnect the connector from the light failure sensor and
ground terminal 4 on the wire harness side connector.
(b) Start the engine, check that the warning light lights up.
If the warning light does not light up, test the bulb or inspect
wire harness.
± BODY ELECTRICAL SYSTEMCOMBINATION METERBE±53

OPEN DOOR WARNING INSPECTION
1. INSPECT DOOR COURTESY SWITCH
 
 Switch Position
 
 
Tester connection to
terminal number 
 Specified condition
 
 ON
(Switch pin released) 
 1±2
2±3 
 Continuity
 
 OFF
(Switch pin pushed in) 
 ±
 
 No continuity
If continuity is not as specified, replace the switch.
2. INSPECT WARNING LIGHT
Disconnect the connector from the door courtesy switch, and
ground terminal 1 on the wire harness side connector and
check that the warning light lights up.
If the warning light does not light up, inspect the bulb or wire
harness.
LIGHT CONTROL RHEOSTAT
INSPECTION
INSPECT LIGHT CONTROL RHEOSTAT
(a) Connect the positive (+) lead from the battery to terminal 1
and negative lead (±) to terminal 3.
(b) Connect the positive (+) lead from the voltmeter to terminal
2 and negative lead to terminal 3.
(c) Turn the rheostat knob and check that the voltage changes. BE±54
± BODY ELECTRICAL SYSTEMCOMBINATION METER

SEAT BELT WARNING INSPECTION
1. INSPECT INTEGRATION RELAY OPERATION
(a) Connect the positive (+) lead from the battery to terminals 1
and 7.
(b) Connect the positive (+) lead from the battery to terminal 9
through a 3.4W test bulb.
(c) Check that the test bulb lights up and buzzer sounds for 4±8
seconds when the negative (±) lead from the battery is
connected to terminal 10.
(d) Check that the buzzer sounding in (c) stops when the
negative (±) lead from the battery is connected to terminal 8.
If operation is not as specified, replace the integration relay.
2. INSPECT RELAY CIRCUIT
Remove the relay from the junction block No.1 and inspect
the connectors on the junction block side.
 
 Tester connection to
terminal number 
 Condition
 
 Specified condition
 4±Ground Driver's door open Continuity 
 4±Ground
 
 Driver's door close
 
 No continuity
 5±Ground Ignition key Set Continuity
 5±Ground Ignition key remove No continuity
 8±Ground Driver's seat belt fasten Continuity 
 8±Ground
 
 Driver's seat belt unfasten
 
 No continuity
 10±Ground Constant Continuity
 1±Ground Constant Battery positive voltage
 9±Ground Ignition switch position ON Battery positive voltage 
 9±Ground
 
 Ignition switch position LOCK or ACC
 
 No voltage
If circuit is not as specified, try replacing the relay with a new
one.
± BODY ELECTRICAL SYSTEMCOMBINATION METERBE±55

3. INSPECT BUCKLE SWITCH CONTINUITY
(a) Check that there is continuity between terminals 1 and 2 on
the switch side connector with the switch ON (belt fastened).
(b) Check that there is no continuity between terminals 1 and 2
on the switch side connector with the switch OFF (belt
unfastened).
If operation is not as specified, replace the seat belt inner
belt.
If the circuit is not as specified, inspect the circuits connected
to other parts. BE±56
± BODY ELECTRICAL SYSTEMCOMBINATION METER

SEAT HEATER SYSTEM
PARTS LOCATION
± BODY ELECTRICAL SYSTEMSEAT HEATER SYSTEMBE±57

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 re-
place the part when it is found to be faulty.
 
 Trouble
 
 Parts name (See page)
 
 
Seat heaters do not operate
(Driver's and Passenger's) 
 
1. SEAT HTR Fuse (BE±6)
2. Wire Harness
 
 
 
Driver's seat heater does not operate
 
 
 
1. Seat Heater Switch (Driver's) (BE±58)
2. Seat Heater (BE±59)
3. Wire Harness
 
 
 
Passenger 's seat heater does not operate
 
 
 
1. Seat Heater Switch (Passenger's) (BE±58)
2. Seat Heater (BE±59)
3. Wire Harness
 Seat heater temperature is too hot 1. Seat Heater (BE±59)
SEAT HEATER SWITCH INSPECTION
1. INSPECT SWITCH CONTINUITY
 
 Condition
 
 Tester connection to
terminal number 
 Specified condition
 Switch ON (LEFT) 2±4  Continuity 
 Switch ON (RIGHT)
 
 4±6
 
  Continuity
 Switch OFF ±  No continuity
 Illumination circuit 3±5  Continuity
If continuity is not as specified, replace the switch or bulb.
2. INSPECT SWITCH INDICATOR
(a) Connect the positive (+) lead from the battery to terminal 2
and 6 and the negative (±) lead to terminal 1.
(b) Push the switches, check that the indicator lights up. If
operation is not as specified, replace the switch and inspect
the circuits connected to other parts. BE±58
± BODY ELECTRICAL SYSTEMSEAT HEATER SYSTEM