Lexus SC300 / Lexus SC400. Manual - part 863

OK

NG

OK

NG

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].

–

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 

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

–

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

NG

OK

OK

NG

9

Disconnect igniter connector and check voltage between terminals IGT1, 2 of engine & ECT
ECU connector and body ground.

C

OK

P

Disconnect igniter connector.

Connect engine & ECT ECU connector.

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)

Replace igniter .*1

10

Check for Open and short in harness and connector in IGT signal circuit between engine & ECT
ECU and igniter (See page 

IN–27

).

Repair or replace harness or connector.

Check and replace engine & ECT ECU.

*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–60

–

ENGINE TROUBLESHOOTING

Circuit Inspection