Lexus SC300 / Lexus SC400. Manual - part 667

OK

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OK

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OK

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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 

IN–27

)

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 

TR–30

).

(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 

TR–30

).

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

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6

Check for open and short in harness and connector between ignition relay and ignition coil,
ignition coil and igniter (See page 

IN–27

).

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.

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ENGINE TROUBLESHOOTING

Circuit Inspection

TR–59