1997 TOYOTA SUPRA engine

DI-300
- DIAGNOSTICSENGINE (2JZ-GTE)
528 Author
: Date
:
1997 SUPRA (RM502U)
DTC P1780 Park/Neutral Position Switch Malfunction
CIRCUIT DESCRIPTION
The park/neutral position switch goes on when the shift lever is in the N or P shift position. When it goes on
terminal NSW of the ECM is grounded to body ground via the starter relay thus the terminal NSW voltage
becomes 0 V. When the shift lever is in the D, 2, L or R position, the park/neutral position switch goes off,
so the voltage of ECM terminal NSW becomes battery voltage, the voltage of the ECM internal power source.
If the shift lever is moved from the N position to the D position, this signal is used for air-fuel ratio correction
and for idle speed control (estimated control), etc.
DTC No.DTC Detecting ConditionTrouble Area
2 or more switches are ON simultaneously for ºNº, º2º and ºLº
position
(2 trip detection logic)
Sh t i k/ t l iti it h i it
P1780When driving under conditions (a) and (b) for 30 sec. or more
the park/neutral position switch is ON (N position)
(2 trip detection logic)
(a) Vehicle speed: 70 km/h (44 mph) or more
(b) Engine speed: 1,500 ~ 2,500 rpm
Short in park/neutral position switch circuit

Park/neutral position switch

ECM
HINT:
After confirming DTC P1780 use the TOYOTA hand-held tester to confirm the PNP switch signal from ºCUR-
RENT DATAº.
WIRING DIAGRAM
Refer to page DI-373 for the WIRING DIAGRAM
INSPECTION PROCEDURE
Refer to page DI-373 for the INSPECTION PROCEDURE
DI4TS-01

S05425
Battery 1
B
2A
AM232
MAIN
5
1
Starter Relay
2 2 2 2
W-R
4IB1
W-R
Ignition Switch 78
B-W
J/B No.1 64
ST
1J1KBB13
IJ2B-WB(for MT)
1
2Clutch
Start
Switch
B-W
2
IJ1
BBB B B
B
R/B No.2
L-O810 254
W-B
L-O
L-O
Theft Deterrent
and Door Lock
Control ECU
IH
IB3 IF2
T3T7
Starter 1
S3 B 3
EA1
EA2
1
B
5 6(for AT)
Park/
Neutral
Position
SwitchECM
STA
E1 77
B
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-301
529 Author
: Date
:
1997 SUPRA (RM502U)
Starter Signal Circuit
CIRCUIT DESCRIPTION
When the engine is cranked, the intake air flow is slow, so fuel vaporization is poor. A rich mixture is therefore
necessary in order to achieve good startability. While the engine is being cranked, the battery positive volt-
age is applied to terminal STA of the ECM. The starter signal is mainly used to increase the fuel injection
volume for the starting injection control and after-start injection control.
WIRING DIAGRAM
DI4TT-01

DI-302
- DIAGNOSTICSENGINE (2JZ-GTE)
530 Author
: Date
:
1997 SUPRA (RM502U)
INSPECTION PROCEDURE
HINT:
This diagnostic chart is based on the premise that the engine is cranked normally. If the engine is not
cranked, proceed to the matrix chart of problem symptoms on page DI-169.
TOYOTA hand-held tester
1 Connect the TOYOTA hand-held tester and check STA signal.
PREPARATION:
(a) Connect the TOYOTA hand-held tester to the DLC3.
(b) Turn ignition switch ON and push TOYOTA hand-held tester main switch ON.
CHECK:
Read STA signal on the TOYOTA hand-held tester while starter operates.
Ignition Switch PositionONSTART
STA SignalOFFON
OK Proceed to next circuit inspection shown on
matrix chart (See page DI-169).
NG
2 Check for open in harness and connector between ECM and starter relay
(See page IN-28).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-28).

S04081BE6653A03406
START
Check Harness A
ECM
B77
STA(+)
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-303
531 Author
: Date
:
1997 SUPRA (RM502U)
OBDII scan tool (excluding TOYOTA hand-held tester)
1 Check voltage between terminal STA of ECM connector and body ground.
PREPARATION:
Connect Check Harness A (See page DI-164).
CHECK:
Measure voltage between terminal STA of ECM connector and
body ground, during engine cranking.
OK:
Voltage: 6.0 V or more
OK Proceed to next circuit inspection shown on
matrix chart (See page DI-169).
NG
2 Check for open in harness and connector between ECM and starter relay
(See page IN-28).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-28).

S03470
Battery
B
12A
AM2
EFI No.1R/B
No.2 22
W-R
4
IB1W-R7
6
Ignition
Switch
B-W
W-B
B-W
2
2
2 2
EB
EFI Main Relay5
1 3
2 3
1J1E8
IGN
J/B No.1B-O13
II1B-O1
31
24
69A
A
A
B
BR B-Y B-RB-R
GR
EA2
EA1
R/B No.2
ED
E1 M-RELB+ +BE1 IGSWECM
2
8 DI-304
- DIAGNOSTICSENGINE (2JZ-GTE)
532 Author
: Date
:
1997 SUPRA (RM502U)
ECM Power Source Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned ON, battery positive voltage is applied to the coil, closing the contacts of
the EFI main relay (Marking: EFI) and supplying power to the terminals +B of the ECM.
WIRING DIAGRAM
DI4TU-01

A00729
ON
Check Harness A
ECM
A31
+B
B69
E1(-)
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-305
533 Author
: Date
:
1997 SUPRA (RM502U)
INSPECTION PROCEDURE
1 Check voltage between terminals +B and E1 of ECM connector.
PREPARATION:
(a) Connect Check Harness A (See page DI-164).
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminals +B and E1 of ECM connec-
tor.
OK:
Voltage: 9 - 14 V
OK Proceed to next circuit inspection shown on
matrix chart (See page DI-169).
NG
2 Check for open in harness and connector between terminal E1 of ECM connector
and body ground (See page IN-28).
NG Repair or replace harness or connector.
OK

A00730
ONCheck Harness A
ECM
A1
IGSW(+)
N08417
J/B No.1
IGN Fuse
DI-306
- DIAGNOSTICSENGINE (2JZ-GTE)
534 Author
: Date
:
1997 SUPRA (RM502U)
3 Check voltage between terminal IGSW of ECM connector and body ground.
PREPARATION:
Turn ignition switch ON.
CHECK:
Measure voltage between terminal IGSW of ECM and body
ground.
OK:
Voltage: 9 - 14 V
OK Go to step 6.
NG
4 Check IGN fuse.
PREPARATION:
Remove IGN fuse from J/B No.1.
CHECK:
Check continuity of IGN fuse.
OK:
Continuity
NG Check for short in all the harness and compo-
nents connected to IGN fuse.
OK

A00731
ONCheck Harness A
ECM
A24 M-REL (+)
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-307
535 Author
: Date
:
1997 SUPRA (RM502U)
5 Check ignition switch (See page BE-13).
NG Replace ignition switch.
OK
Check for open and short in harness and connector between battery and ignition switch, ignition
switch and ECM (See page IN-28).
6 Check voltage between terminal M-REL of ECM connector and body ground.
PREPARATION:
Turn ignition switch ON.
CHECK:
Measure voltage between terminal M-REL of ECM and body
ground.
OK:
Voltage: 9 - 14 V
NG Check and replace ECM.
OK
7 Check EFI fuse (See page DI-284).
NG Check for short in all the harness and compo-
nents connected to EFI fuse.
OK