Page 649 of 1807
A00712
ONCheck Harness AECM
B74
EVAP(+)
DI-236
- DIAGNOSTICSENGINE (2JZ-GTE)
464 Author: Date:
1997 SUPRA (RM502U)
4 Check connection of vacuum hose (See page EC-5).
NG Repair or replace.
OK
Check and repair charcoal canister (See
page EC-5).
OBDII scan tool (excluding TOYOTA hand-held tester)
1 Check VSV for EVAP (See page SF-71).
NG Replace VSV for EVAP.
OK
2 Check voltage between terminal EVAP of ECM connector and body ground.
PREPARATION:
(a) Connect Check Harness A (See page DI-164).
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminal EVAP of ECM connector
and body ground.
OK:
Voltage: 9 - 14 V
NG Check and repair harness or connector.
OK
Page 650 of 1807
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-237
465 Author: Date:
1997 SUPRA (RM502U)
3 Check connection of vacuum hose (See page EC-5).
NG Repair or replace.
OK
4 Check charcoal canister (See page EC-5).
NG Repair or replace.
OK
Check and replace ECM (See page IN-28).
Page 651 of 1807

Q04361 FI6643A03136
T/M4-Pulse 4-Pulse
ECM
Combination
Meter No.1 Vehicle
Speed MeterTransmission
Output Shaft
Driven Gear
No.1 Vehicle Speed Sensor
S01080
GAUGE Fuse
23
II1
YY
Y
1
1
2No.1 Vehicle
Speed Sensor
Speed Meter3
L-R
II12
L-R5
Odometer and
Trip Meter
Telltale Light RH6
P11
II1P2
ASP1ECM
5V
E1 DI-238
- DIAGNOSTICSENGINE (2JZ-GTE)
466 Author: Date:
1997 SUPRA (RM502U)
DTC P0500 Vehicle Speed Sensor Malfunction
CIRCUIT DESCRIPTION
The No.1 vehicle speed senor outputs a 4-pulse signal for every revolution of the rotor shaft, which is rotated
by the transmission output shaft via the driven gear. After this signal is converted into a more precise rectan-
gular waveform by the waveform shaping circuit inside the combination meter, it is then transmitted to the
ECM. The ECM determines the vehicle speed based on the frequency of these pulse signals.
DTC No.DTC Detecting ConditionTrouble Area
P0500
No vehicle speed sensor signal to ECM under the following
conditions:
(2 trip detection logic)
(a) Park/neutral position switch is OFF
(b) Vehicle is being drivenOpen or short in vehicle speed sensor circuit
Vehicle speed sensor
Combination meter
ECM
WIRING DIAGRAM
DI4T7-01
Page 652 of 1807

A00714
ONCheck Harness A
ECM
A2 SP1(+)
AT7809
4.5 - 5.5 V
0Turn the wheel
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-239
467 Author: Date:
1997 SUPRA (RM502U)
INSPECTION PROCEDURE
1 Check operation of speedometer.
CHECK:
Drive the vehicle and check if the operation of the speedometer in the combination meter is normal.
HINT:
The No.1 vehicle speed sensor is operating normally if the speedometer display is normal.
NG Check speedometer circuit (See page BE-43).
OK
2 Check voltage between terminal SP1 of ECM connector and body ground.
PREPARATION:
(a) Shift the shift lever to neutral position.
(b) Jack up one of rear wheels.
(c) Connect Check Harness A (See page DI-164).
(d) Disconnect power steering ECU connector and cruise
control ECU connector.
(e) Turn ignition switch ON.
CHECK:
Measure voltage between terminal SP1 of ECM connector and
body ground when rear wheel is turned slowly.
OK:
Voltage is generated intermittently.
NG Check and repair harness and connector be-
tween combination meter and ECM.
OK
Check and replace ECM (See page IN-28).
Page 653 of 1807

FI6973
Throttle Body
Chamber
From
Air
Flow
Meter
To
Cylinder Head
Valve ShaftRotorCoilsValveThrottle
Valve
Air Intake
S03465
Battery
B
W-B
EB
EFI No.1
2A2
R/B
No.2
B-W
22 2
2
5
1
3 2B-Y B-R2
B-R
EA2
EA18
GR24
35
33
34
32A
B
B
B
B
B-R
5
2B1
B2S1
S3
S2
S44
6
1 3
IAC ValveV-Y
G-O
G-W
R-GE01 ISC1
M-REL
B+ ECM
ISC3
ISC2
ISC4
1
EFI Main Relay
R/B
No.2 DI-240
- DIAGNOSTICSENGINE (2JZ-GTE)
468 Author: Date:
1997 SUPRA (RM502U)
DTC P0505 Idle Control System Malfunction
CIRCUIT DESCRIPTION
The step motor type IAC valve is located in front of the intake
air chamber. Intake air bypassing the throttle valve is directed
to the IAC valve through a passage. A step motor is built into
the IAC valve. It consists of 4 coils, a magnetic rotor, valve shaft
and valve.
When current flows to the coils due to signals from the ECM, the
rotor turns and moves the valve shaft forward or backward,
changing the clearance between the valve and the valve seat.
In this way the intake air volume bypassing the throttle valve is
regulated, controlling the engine speed.
There are 125 possible positions to which the valve can be
opened.
DTC No.DTC Detecting ConditionTrouble Area
P0505Idle speed continues to vary greatly from the target speed
(2 trip detection logic)
IAC valve is stuck or closed
Open or short in IAC valve circuit
Open or short in A/C signal circuit
Air intake (hose loose)
WIRING DIAGRAM
DI4T8-01
Page 654 of 1807
A00202
A/C Switch OFF " ON
(IAC Valve Open)
A/C Switch ON " OFF
(IAC Valve Close)
20 V/Division
20 V/Division ISC1
ISC2
ISC3
ISC4
ISC1
ISC2
ISC3
ISC4
10 msec./Division
10 msec./Division
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-241
469 Author: Date:
1997 SUPRA (RM502U)
Reference INSPECTION USING OSCILLOSCOPE
With engine idling measure waveforms between termi-
nals ISC1, ISC2, ISC3, ISC4 and E01 of ECM when A/C
switch ON or OFF.
HINT:
The correct waveforms are as shown.
INSPECTION PROCEDURE
1 Check air induction system (See page SF-1).
NG Repair or replace.
OK
Page 655 of 1807
A00715
ON
Check Harness A
B35, 34, 33, 32
ISC1(+)
ISC2(+)ISC3(+)
ISC4(+)
DI-242
- DIAGNOSTICSENGINE (2JZ-GTE)
470 Author: Date:
1997 SUPRA (RM502U)
2 Check voltage between terminals ISC1, ISC2, ISC3, ISC4 of ECM connector and
body ground.
PREPARATION:
(a) Connect Check Harness A to the connectors on the wire
harness side (See page DI-164).
HINT:
The other side of Check Harness A is not connected to the ECM
terminals.
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminals ISC1, ISC2, ISC3, ISC4 of
ECM connector and body ground.
OK:
Voltage: 9 - 14 V
OK Go to step 4.
NG
3 Check IAC valve (See page SF-52).
NG Replace IAC valve.
OK
Check for open and short in harness and connector between EFI main relay (Marking: EFI MAIN)
and IAC valve, IAC valve and ECM (See page IN-28).
4 Check operation of the IAC valve (See page SF-52).
NG Repair or replace IAC valve.
OK
Check and replace ECM (See page IN-28).
Page 656 of 1807

- DIAGNOSTICSENGINE (2JZ-GTE)
DI-243
471 Author: Date:
1997 SUPRA (RM502U)
DTC P0510 Closed Throttle Position Switch Malfunction
CIRCUIT DESCRIPTION
Refer to ºThrottle/Pedal Position Sensor/Switch ºAº Circuit Malfunctionº on page DI-184.
DTC No.DTC Detecting ConditionTrouble Area
P0510
The closed throttle position switch does not turn ON or OFF
even once when the vehicle is driven
(2 trip detection logic)Open or short in closed throttle position switch circuit
Closed throttle position switch
ECM
HINT:
After confirming DTC P0510 use the TOYOTA hand-held tester to confirm the closed throttle position switch
signal from ºCURRENT DATAº.
Throttle ValveClosed throttle position switch signalMalfunction
Fully ClosedOFFOpen Circuit
Fully OpenONShort Circuit
WIRING DIAGRAM
Refer to page DI-184 for the WIRING DIAGRAM.
INSPECTION PROCEDURE
HINT:
If DTC P0110, P0115 and P0120 are output simultaneously, E2 (sensor ground) may be open.
TOYOTA hand-held tester
1 Connect the TOYOTA hand-held tester and read CTP switch signal.
PREPARATION:
(a) Connect the TOYOTA hand-held tester to the DLC3.
(b) Turn ignition switch ON and push the TOYOTA hand-held tester main switch ON.
CHECK:
Read CTP switch signal on the TOYOTA hand-held tester.
RESULT:
Throttle ValveClosed throttle position switch signalMalfunction
Fully ClosedOFFOpen Circuit: Go to step 2.
Fully OpenONOpen Circuit: Go to step 4.
DI4T9-01