1995 TOYOTA SUPRA ignition

ECM Power Source Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned on, battery volt-
age is applied to the terminal IGSW of the ECM,
and the main relay control circuit in the ECM sends
a signal to the terminal M±REL of the ECM, switch-
ing on the main relay. This signal causes current to
flow to the coil, closing the contacts of the main
relay and supplying power to the terminal + B of the
ECM.
If the ignition switch is turned off, the ECM contin-
ues to switch on the main relay for a maximum of
2 seconds for the initial setting of the IAC valve. EG±576
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

(See page EG±510)
(1) Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
(2) Turn ignition switch ON.
Measure voltage between terminal +B and E1 of
engine control module connector.
Voltage: 9 Ð 14 V
Check voltage between terminal +B and E1 of engine control module
connector.
Proceed to next circuit inspection shown on
matrix chart (See page EG±514).
Repair or replace harness or connector.
Check for open in harness and connector between terminal E1 of engine
control module and body ground (See page IN±30).
Turn ignition switch ON.
Measure voltage between terminal IGSW of en-
gine control module connector and body ground.
Voltage: 9 Ð 14 V
Check voltage between terminal IGSW of engine control module connector
and body ground.
INSPECTION PROCEDURE
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±577

Check for short in the harness and all the compo-
nents connected to IGN fuse (See Electrical Wir-
ing Diagram).
Remove IGN fuse from J/B No.1.
Check continuity of IGN fuse.
Continuity
Check IGN fuse.
Check ignition switch.
(1) Remove finish lower panel and finish lower
panel LH.
(2) Remove heater to register duct No.2.
Check continuity between terminals.
Check and repair harness and connector between
battery and ignition switch, ignition switch and en-
gine control module.
Replace ignition switch.
Terminal
Switch position
LOCK
ACC
ON
START
continuity
EG±578± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

Check for short in the harness and all the compo-
nents connected to EFI No.1 fuse (See Electrical
Wiring Diagram).
Turn ignition switch ON.
Measure voltage between terminal M±REL of en-
gine control module connector and body ground.
Voltage: 9 Ð 14 V
Check voltage between terminal M±REL of engine control module connector
and body ground
Check EFI No.1 Fuse.
Remove EFI No.1 fuse from R/B No.2.
Check continuity of EFI No.1 fuse.
Continuity
Check and replace engine control module.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±579

Back Up Power Source Circuit
CIRCUIT DESCRIPTION
Battery positive voltage is supplied to terminal BATT of the ECM even when the ignition switch is off for use by
the diagnostic trouble code memory and air±fuel ratio adaptive control value memory, etc.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±581

INSPECTION PROCEDURE
(See page EG±510)
Check and repair harness or connector between
engine control module and EFI No.1 fuse, EFI No.1
fuse and battery.
Remove EFI No.1 fuse from R/B No.2.
Check continuity of EFI No.1 fuse.
Continuity
Check EFI No.1 Fuse.
Check voltage between terminal BATT of engine control module connector
and body ground.
Connect SST (check harness ªAº).
See page EG±510)
SST 09990±01000
Measure voltage between terminal BATT of en-
gine control module connector and body ground.
Voltage: 9 Ð 14 V
Check for short in the harness and all the compo-
nents connected to EFI No.1 fuse (See attached
wiring diagram).
Are the diagnostic trouble codes still in the memory when the ignition switch
is turned OFF?
Check and replace engine control module.
Proceed to next circuit inspection shown on matrix
chart (See page EG±514).
EG±582± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

INSPECTION PROCEDURE
Remove AM2 fuse from R/B No.2.
Check continuity of AM2 fuse.
Continuity
Check voltage between terminals # 10 ~ 60 of engine control module and
body ground.
Check AM2 fuse.
(1) Connect SST (check harness ªAº).
See page EG±510)
SST 09990±01000
(2) Turn ignition switch ON.
Measure voltage between terminals # 10 ~ 60 of en-
gine control module and body ground.
Voltage: 9 Ð 14 V
Check for short in the harness and all the components
connected to AM2 fuse.
EG±584± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

(See page EG±510)
(See page IN±30).
(1) Connect SST (check harness ªAº).
(See page EG±510)
(2) Turn ignition switch ON.
Measure voltage between terminal VSV1, VSV2,
VSV3 of engine control module connector and
body ground.
Voltage: 9 Ð 14 V
Check voltage between terminal VSV1, VSV2, VSV3 of engine control
module connector and body ground.
Check actuator. (See page EG±144, 158)
Repair or replace harness or connector.
Check for open and short in harness and connector between EFI main replay
and engine control module (See page IN±30).
Check and replace engine control module. EG±594
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING