Page 697 of 1807
FI6878
R/B No.2
EFI No.1 2A2 1
Battery
B
B-Y
EA14
B-Y33
AECM
BATT DI-282
- DIAGNOSTICSENGINE (2JZ-GTE)
510 Author: Date:
1997 SUPRA (RM502U)
DTC P1600 ECM BATT Malfunction
CIRCUIT DESCRIPTION
Battery positive voltage is supplied to terminal BATT of the ECM even when the ignition switch is OFF for
use by the DTC memory and air-fuel ratio adaptive control value memory, etc.
DTC No.DTC Detecting ConditionTrouble Area
P1600Open in back up power source circuitOpen in back up power source circuit
ECM
HINT:
If DTC P1600 appear, the ECM does not store another DTC.
WIRING DIAGRAM
DI4TL-01
Page 698 of 1807
A00727
LOCK
Check Harness A
ECM
A33
BATT(+)
N08419
EFI FuseR/B No.2
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-283
511 Author: Date:
1997 SUPRA (RM502U)
INSPECTION PROCEDURE
1 Check voltage between terminal BATT of ECM connector and body ground.
PREPARATION:
Connect Check Harness A (See page DI-164).
CHECK:
Measure voltage between terminal BATT of ECM connector
and body ground.
OK:
Voltage: 9 - 14 V
OK Check and replace ECM (See page IN-28).
NG
2 Check EFI fuse.
PREPARATION:
Remove EFI fuse from R/B No.2.
CHECK:
Check continuity of EFI fuse.
OK:
Continuity
NG Check for short in all the harness and compo-
nents connected to EFI fuse.
OK
Check and repair harness or connector be-
tween battery, EFI fuse and ECM.
Page 699 of 1807
DI-284
- DIAGNOSTICSENGINE (2JZ-GTE)
512 Author: Date:
1997 SUPRA (RM502U)
DTC P1605 Knock Control CPU Malfunction
CIRCUIT DESCRIPTION
Refer to Knock Sensor 1, 2 Circuit Malfunction on page DI-209.
DTC No.DTC Detecting ConditionTrouble Area
P1605Engine control computer malfunction
(for knock contorl)ECM
WIRING DIAGRAM
Refer to page DI-209 for WIRING DIAGRAM.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P1605) being output?
YES Go to relevant DTC chart.
NO
Check and replace ECM. (See page IN-28).
DI4TM-01
Page 700 of 1807

S03451
ECM
EFI+
EFI-
ETC+
ETC-27
26
14
13A
A
A
AB
W
Y
W-RThrottle Control ECU
EFI+
EFI-
GE11
ETC+
ETC-
GE12
T15
T15
T15
T15
T15
T15
7
20
15
8
21
14
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-285
513 Author: Date:
1997 SUPRA (RM502U)
DTC P1630 Traction Control System Malfunction
CIRCUIT DESCRIPTION
This circuit is used send TRAC control information from throttle control ECU to the ECM (ETC+, ETC-), and
engine control information from the ECM to the throttle control ECU (EFI+, EFI-).
DTC No.DTC Detecting ConditionTrouble Area
P1630
Condition (a) or (b) continued for 5 sec. or more
(a) No EFI ± data is received from the ECM.
(b) A signal is received from the ECM indicating trouble in
TRAC.Open or short in ETC+ or ETC- circuit
Open or short in EFI+ or EFI- circuit
Throttle control ECU
ECM
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
When TRAC OFF indicator is OFF, there is a problem in the EFI ± circuit, and when the TRAC OFF indicator
is ON, there is problem in the ETC ± circuit.
1 Check TRAC system (See page DI-501).
NG Repair or replace TRAC systems.
OK
DI4TN-01
Page 701 of 1807
S03407S03406
A03150
1 V/Division
2 V/Division
EFI+, EFI- SIgnal Waveform
ETC+, ETC- SIgnal Waveform EFI+
0
EFI-
0
1 msec./Division
(Idling or IG switch ON)
1 msec./Division
(Idling or IG switch ON) ETC+
0
ETC-
0
DI-286
- DIAGNOSTICSENGINE (2JZ-GTE)
514 Author: Date:
1997 SUPRA (RM502U)
2 Check for open and short in harness and connector between terminals EFI+,
EFI-, ETC+ and ETC- of throttle control ECU and ECM (See page IN-28).
Reference INSPECTION USING OSCILLOSCOPE
With engine idling or IG switch ON measure waveforms
between terminals EFI+, EFI- and E2 of ECM.
With engine idling or IG switch ON measure waveforms
between terminals ETC+, ETC- and E2 of ECM.
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-28).
Page 702 of 1807
S03236
CAC Air Bypass ValveAir
CleanerECM
Pressure
Tank
Intake
Air Control Valve (IACV)
Actuator (for IACV)
VSV for IACV
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-287
515 Author: Date:
1997 SUPRA (RM502U)
DTC P1652 IACV Control Circuit Malfunction
CIRCUIT DESCRIPTION
The valve controls the opening or closing of the No.2 intake air passage in order to pass the charge air from
No.2 turbocharger.
DTC No.DTC Detecting ConditionTrouble Area
P1652
During idling, voltage level at the output terminal (VSV1) of
ECM is low
(2 trip detection logic)Open or short in VSV circuit for IACV
VSV for IACV
ECM
DI4TO-01
Page 703 of 1807
S03469
Battery
EB
B
2A2
1 R/B
No.2
EFI No.1B-W
22 R/B
No.2
35
2 2 2
1 B-R
B-Y5
EA2B-R
8
EA1B-R
EFI Relay
12
G-R38
BVSV3B+ ECM
E01
M-RELVSV2
VSV1E01
B+ E01 39
B
40
B
24
A VSV for Exhaust
Bypass Valve
G-Y
G-B 1
12
2 B-R
B-R
B-R
GR
W-B
VSV for Exhaust
Gas Control Valve
VSV for Intake
Air Control Valve
DI-288
- DIAGNOSTICSENGINE (2JZ-GTE)
516 Author: Date:
1997 SUPRA (RM502U)
WIRING DIAGRAM
Page 704 of 1807

BE6653S03252S03253
A03147
ON
Air
Air
Air Filter
E
E
F
VSV: ON
VSV: OFF
- DIAGNOSTICSENGINE (2JZ-GTE)
DI-289
517 Author: Date:
1997 SUPRA (RM502U)
INSPECTION PROCEDURE
TOYOTA hand-held tester
1 Connect the TOYOTA hand-held tester and check operation of VSV for IACV.
PREPARATION:
(a) Connect the TOYOTA hand-held tester to DLC3.
(b) Turn ignition switch ON and TOYOTA hand-held tester
main switch ON.
(c) Select the ACTIVE TEST mode on the TOYOTA hand-
held tester.
CHECK:
Check operation of VSV when VSV is operated by the TOYOTA
hand-held tester.
OK:
VSV is ON:
Air from pipe E flows out through pipe F.
VSV is OFF:
Air from pipe E flows out through the air filter.
OK Check for intermittent problems
(See page DI-147).
NG
2 Check VSV for IACV (See page SF-61).
NG Replace VSV for IACV.
OK
3 Check for open and short in harness and connector between EFI main relay
(Marking: EFI MAIN) and ECM (See page IN-28).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-28).