Toyota Land Cruiser 1988 Repair Manual page 171

Fl-40 EFI SYSTEM -Troubleshooting with Volt/ Ohmmeter
No. Terminals Trouble Condition STD Voltage
8 ISC1 - ISC4 - E1 No voltage
Ignition switch ON 9-14
v
ISC Valve
ECU
Fuse
~----~'-r----------+~ ~------~~~·~~~----~ISC1
Fusible
Link
Battery
EFI 15A
e>
e
Battery
FI0312
®
Fi2356
~~~~~----~ISC2
'+"!lll"-<l......._--...o
IS C3
LJQO'-<>--t::----o
ISC4
.,_. ______
~
+
B
.__ _______
~
+
B1
.__ _ _ _ _ _ _ _ _ _ - ¢
M-REL
r----Q
E1
F12437
CD
There is no voltage between ECU terminals ISC1 - ISC4
and E1. (IG S/W ON)
®
Check that there is voltage between ECU terminal + B
( +
B1) and body ground. (IG S/W ON)
OK
!
NO
Refer to No. 1 .
(See page Fl-30)
Check wiring between ECU terminal E1 and body
ground.
OK
~BAD
fg\ Check ISC valve.
\!V
(See page Fl-71)
Repair or replace.
BAD
!
OK
Replace ISC Check wiring between ECU and EFI
valve. main relay.
!
OK
~BAD
Try another ECU. Repair or replace.