TOYOTA SUPRA 1997 Service Repair Manual

F03378BE6653F03382F03383
ON
(-)
VTA2 (+)
DI-520
- DIAGNOSTICSABS & TRACTION CONTROL SYSTEM
748 Author
: Date
:
1997 SUPRA (RM502U)
INSPECTION PROCEDURE
1 Check voltage between terminal VTA2 of throttle control ECU and body ground.
PREPARATION:
(a) Remove throttle control ECU with connectors still con-
nected.
(b) Remove intake air duct.
(c) Disconnect sub-throttle valve motor connector.
(d) Turn ignition switch ON.
CHECK:
Measure voltage between terminal VTA2 of throttle control ECU
and body ground, when the sub-throttle valve is fully closed
and fully open.
OK:
Sub-throttle valve positionVoltage
Fully closed0.3 - 0.8 V
Fully open3.2 - 4.9 V
OK Go to step 3.
NG
2 Check for open and short in harness and connector between terminal VTA2 of
throttle control ECU and terminal VTO2 of ECM (See page IN-28).
NG Repair or replace harness or connector.
OK
Check and replace throttle control ECU.
3 Check sub-throttle position sensor (See page DI-243).
NG Adjust or replace sub-throttle position sensor
(See page SF-44).
OK

- DIAGNOSTICSABS & TRACTION CONTROL SYSTEM
DI-521
749 Author
: Date
:
1997 SUPRA (RM502U)
4 Check for open and short in harness and connector between terminal E1 of
throttle control ECU and body ground (See page IN-28).
NG Repair or replace harness or connector.
OK
Check and replace throttle control ECU.

F03384
Throttle
Control
ECU
VTA1
12V
IDL1
E1 T15
T15
T156
4
26
BR R V-Y
3 R R E1040
E964 VTO1
IDL1 ECM
EDThrottle Position Sensor DI-522
- DIAGNOSTICSABS & TRACTION CONTROL SYSTEM
750 Author
: Date
:
1997 SUPRA (RM502U)
DTC 31 Throttle Position Sensor Circuit
CIRCUIT DESCRIPTION
This circuit is not directly related to the TRAC control, but as it has an influence on TRAC control when trouble
occurs in this circuit, it is used to switch off the TRAC system as a fail safe function.
DTC No.DTC Detecting ConditionTrouble Area
31Throttle position sensor circuit is open circuit and E1 or +B
circuit is short for 0.5 sec. or more.

Throttle position senor

Wire harness and connector (throttle position sensor and E1
circuit)

Throttle control ECU
WIRING DIAGRAM
DI4W0-01

F03385BE6653F03386F03387
ON
IDL1
- DIAGNOSTICSABS & TRACTION CONTROL SYSTEM
DI-523
751 Author
: Date
:
1997 SUPRA (RM502U)
INSPECTION PROCEDURE
HINT:
The main throttle position sensor signal is transmitted to the throttle control ECU from ECM, so if an error
occurs at the engine side, the throttle control ECU also detects it.
If DTC No. P0120 or P0121 is being output for the engine, troubleshoot the engine first.
1 Is DTC output for the engine?
Check DTC on page DI-147.
YES Repair circuit indicated by the code output.
NO
2 Check voltage between terminal IDL1 of throttle control ECU and body ground.
PREPARATION:
(a) Remove throttle control ECU with connectors still con-
nected.
(b) Disconnect the vacuum hose from the throttle opener,
and apply vacuum to the throttle opener.
(c) Turn ignition switch ON.
CHECK:
Measure voltage between terminal IDL1 of throttle control ECU
and body ground, when the throttle valve is fully closed and fully
open.
OK:
Throttle valve positionVoltage
Fully closed0 - 3 V
Fully open9 - 14 V
OK Go to step 4.
NG

F03385BE6653F03388F03389
ON
VTA1
DI-524
- DIAGNOSTICSABS & TRACTION CONTROL SYSTEM
752 Author
: Date
:
1997 SUPRA (RM502U)
3 Check for open and short in harness and connector between terminal IDL1 of
throttle control ECU and throttle position sensor (See page IN-28).
NG Repair or replace harness or connector.
OK
Check and replace throttle control ECU.
4 Check voltage between terminal VTA1 of throttle control ECU and body ground.
PREPARATION:
(a) Remove throttle control ECU with connectors still con-
nected.
(b) Disconnect the vacuum hose from the throttle opener,
and apply vacuum to the throttle opener.
(c) Turn ignition switch ON.
CHECK:
Measure voltage between terminal VTA1 of throttle control ECU
and body ground, when the throttle valve is fully closed and fully
open.
OK:
Throttle valve positionVoltage
Fully closed0.3 - 0.8 V
Fully open3.2 - 4.9 V
OK Go to step 6.
NG

- DIAGNOSTICSABS & TRACTION CONTROL SYSTEM
DI-525
753 Author
: Date
:
1997 SUPRA (RM502U)
5 Check for open and short in harness and connector between terminals VTA1 of
throttle control ECU and VTO1 of ECM (See page IN-28).
NG Repair or replace harness or connector.
OK
Check and replace throttle control ECU.
6 Check throttle position sensor (See page SF-44).
NG Adjust or replace throttle position sensor
(See page SF-44).
OK
7 Check for open and short in harness and connector between terminal E1 of
throttle control ECU and body ground (See page IN-28).
NG Repair or replace harness or connector.
OK
Check and replace throttle control ECU.

F03376
ECM
VTO2
IDL2
Sub-throttle
Position Sensor 39
E10
E963
GR-R G-O
T1519
GR-R GR-R 3
T15
26
T15BR 12V
VTA2
12V
12V
GE01
E01 B BA A
12V
12V 12
T15
T15
25
T15
T15
23
T15
13
T15 W-B (Shielded)
L
Y
R
B Sub- throttle
Valve Motor
6
4
3
1
2
ED EC
IDL2
E1 11
24
Throttle Control ECU DI-526
- DIAGNOSTICSABS & TRACTION CONTROL SYSTEM
754 Author
: Date
:
1997 SUPRA (RM502U)
DTC 32 Sub-Throttle Position Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the opening angle of the sub-throttle valve and sends the appropriate signals to the
ECU. If a trouble signal is input, the ECU prohibits TRAC control.
DTC No.DTC Detecting ConditionTrouble Area
32
Conditions (1) and (2) continue for 0.5 sec. or more:
(1) Sub-throttle position sensor circuit is open and E1 or +B
circuit is short.
(2) Instead of sub-throttle valve motor is driven fully close,
IDL2 of sub-throttle position sensor will not come ON.
Sub-throttle position senor

Sub-throttle valve motor

Sub-throttle valve

Wire harness and connector (sub-throttle position sensor
and E1 circuit)

Throttle control ECU
WIRING DIAGRAM
DI4W1-01

F03378BE6653F03379F03380
ON
IDL2
- DIAGNOSTICSABS & TRACTION CONTROL SYSTEM
DI-527
755 Author
: Date
:
1997 SUPRA (RM502U)
INSPECTION PROCEDURE
HINT:
The sub-throttle position sensor signal is transmitted to the throttle control ECU from ECM, so if an error
occurs at the engine side, the throttle control ECU also detects it.
If DTC No. P1400 or P1401 is being output for the engine, troubleshoot the engine first.
1 Is DTC output for the engine?
Check DTC on page DI-147.
YES Repair circuit indicated by the code output.
NO
2 Check voltage between terminal IDL2 of throttle control ECU and body ground.
PREPARATION:
(a) Remove throttle control ECU with connectors still con-
nected.
(b) Remove intake air duct.
(c) Disconnect sub-throttle valve motor connector.
(d) Turn ignition switch ON.
CHECK:
Measure voltage between terminal IDL2 of throttle control ECU
and body ground, when the sub-throttle valve is fully closed
and fully open.
OK:
Sub-throttle valve positionVoltage
Fully closed0 - 3 V
Fully open9 - 14 V
OK Go to step 4.
NG
3 Check for open and short in harness and connector between terminal IDL2 of
throttle control ECU and sub-throttle position sensor (See page IN-28).
NG Repair or replace harness or connector.
OK

F03378BE6653F03382F03383
ON
VTA2 (-)(+)
DI-528
- DIAGNOSTICSABS & TRACTION CONTROL SYSTEM
756 Author
: Date
:
1997 SUPRA (RM502U)
4 Check voltage between terminal VTA2 of throttle control ECU and body ground.
PREPARATION:
(a) Remove throttle control ECU with connectors still con-
nected.
(b) Remove intake air duct.
(c) Disconnect sub-throttle valve motor connector.
(d) Turn ignition switch ON.
CHECK:
Measure voltage between terminal VTA2 of throttle control ECU
and body ground, when the sub-throttle valve is fully closed
and fully open.
OK:
Sub-throttle valve positionVoltage
Fully closed0.3 - 0.8 V
Fully open3.2 - 4.9 V
OK Go to step 6.
NG
5 Check for open and short in harness and connector between terminals VTA2 of
throttle control ECU and VTO2 of ECM (See page IN-28).
NG Repair or replace harness or connector.
OK
Check and replace throttle control ECU.
6 Check sub-throttle position sensor (See page DI-243).
NG Adjust or replace sub-throttle position sensor
(See page SF-44).
OK

F03377
63
1
4
- DIAGNOSTICSABS & TRACTION CONTROL SYSTEM
DI-529
757 Author
: Date
:
1997 SUPRA (RM502U)
7 Check sub-throttle valve motor.
PREPARATION:
Disconnect sub-throttle valve motor connector.
CHECK:
Check continuity between each terminal of sub-throttle valve
motor connector.
OK:
Terminals 1 and 3Continuity
Terminls 4 and 6
Continuity
(Reference value 0.40 - 0.48 W)
NG Replace sub-throttle valve motor.
OK
8 Check for open and short in harness and connector between terminal E1 of
throttle control ECU and body ground (See page IN-28).
NG Repair or replace harness or connector.
OK
Check and replace throttle control ECU.