Lexus SC300 / Lexus SC400. Service manual — part 667
OK
NG
OK
NG
OK
NG
INSPECTION PROCEDURE
HINT: If diag. code 14 is displayed, check No. 1 igniter circuit.
If diag. code 15 is displayed, check No. 2 igniter circuit.
1
Check for Spark.
C
OK
Hint
Disconnect the high–tension cord from the distributor,
hold its end about 12.5 mm (1/2”) from the ground, see
if spark occurs while the engine is being cranked.
Spark should be generated.
To prevent excessive fuel injected from the injectors dur-
ing the check. Don’t crank the engine for more than 1–2
seconds at a time.
Go to step [4].
2
Check for open and short in harness and connector in the IGF and IGT signal circuit between
engine & ECT ECU and igniter (See page
)
Repair or replace harness or connector.
#
Disconnect igniter sonnector and check voltage between terminals IGF1, 2 of engine & ECT
ECU connector and body ground.
C
OK
P
(2) Disconnect igniter connector.
(2) Connect the Check Harness A.
(See page
(2) Turn ignition switch on.
Measure Voltage between terminals IGF1, 2 or engine
& ECT ECU connector and body ground.
Voltage:
4 – 6 V
Replace igniter.*1
Check and replace engine & ECT ECU.
*1:
When dia. code 14 is displayed, replace the igniter with 5
wire harness. (extra wire is for tachometer). When diag.
code 15 is displayed, replace the igniter with 4 wire har-
ness.
TR–56
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ENGINE TROUBLESHOOTING
Circuit Inspection
OK
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OK
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4
Check voltage between terminals IGT1, 2 of engine and & ECT ECU connector and body ground.
C
OK
P
Connect the Check Harness A.
(See page
Measure voltage between terminals IGT1, 2 of engine
& ECT ECU connector and body ground when engine
is cranked.
Voltage:
0.5 – 1.0 V
(Neither 0 V nor 5 V)
Go to step [9].
5
Check voltage between terminal 3 of No. 1, No. 2 igniter connectors and body ground.
C
OK
P
Disconnect igniter connector.
Mesure voltage between terminal 3 of No. 1, No. 2 igni-
ter connectors and body ground, when ignitino switch is
turned to “ON” and “STA” position.
Voltage:
10 – 14 V
Go to step [8].
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ENGINE TROUBLESHOOTING
Circuit Inspection
TR–57
OK
NG
OK
NG
6
Check for open and short in harness and connector between ignition relay and ignition coil,
ignition coil and igniter (See page
).
Repair or replace harness or connector
#
Check ignition coil.
C
OK
P
Disconnect ignition coil connector.
(For No. 1 ignition coil (on left bank), remove the battery)
(2) Check primary coil.
Measure resistance between terminals of ignition
coil connector.
(2) Check secondary coil.
Measure resistance between terminal 1 of ignition
coil connector and high–tension terminal.
Replace ignition coil.
Replace Igniter. *1
*1:
When diag. code 14 is displayed, replace the igniter with
5 wire harness. (extra wire is for tachometer). When diag.
code 15 is displayed, replace the igniter with 4 wire har-
ness
TR–58
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ENGINE TROUBLESHOOTING
Circuit Inspection
OK
NG
8
Check Ignition Relay.
C
OK
P
C
OK
Remove ignition relay.
Check continuity between terminals of ignition relay
shown below.
(2) Apply battery voltage between terminals 3 and 6, 4
and 5.
(2) Check continuity between terminals 1 and 2.
Replace ignition relay.
Check and repair harness or connector between
battery and ignition relay, ignition relay and igni-
ter.
–
ENGINE TROUBLESHOOTING
Circuit Inspection
TR–59
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