Lexus SC300 / Lexus SC400. Manual — part 738

NG

OK

OK

NG

OK

NG

INSPECTION PROCEDURE

1

Check voltage between terminals M1, M2 and ECU–E of ECU connector.

C

OK

P

Remove ECU with connectors still connected.

Measure voltage between terminals M1, M2 and ECU–
E of ECU connector when memory & return switches is
on and off.

Proceed to next circuit inspection shown on matrix chart
(See page

SR–52

).

2

Check memory & return switches.

C

OK

P

Disconnect driving position memory & return switches
connector.

Measure resistance between terminals M2, M1 and E of
driving position memory & return switches connector
when memory & return switches is on and off.

Replace memory & return switches.

3

Check harness and connector between ECU and memory & return switches (See page

IN–33

).

Repair or replace harness or connector.

Check and replace ECU.

–

STEERING

STEERING COLUMN

SR–91

SR–52

).

WIRING DIAGRAM

Ignition Switch Circuit

CIRCUIT DESCRIPTION

The ON, OFF signal from the IG switch is sent to the ECU.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

SR–92

–

STEERING

STEERING COLUMN

NG

OK

OK

NG

INSPECTION PROCEDURE

1

Check voltage between terminal IG of ECU connector and body ground.

C

OK

P

Remove ECU with connectors still connected.

Measure voltage between terminal EG of ECU connec-
tor and body ground when ignition switch is on and off.

Proceed to next circuit inspection shown on matrix chart
(See page

SR–52

.)

2

Check ECU–IG fuse.

C

OK

P

Remove ECU–IG fuse from J/B No. 1.

Check continuity of ECU–IG fuse.

Continuity

Check for short in all the harness and components con-
nected to ECU–IG fuse.

Check and repair harness or connector between
ECU and battery.

–

STEERING

STEERING COLUMN

SR–93

SR–52

).

BE–168

.

WIRING DIAGRAM

Park/Neutral Position Switch Circuit

CIRCUIT DESCRIPTION

The park/neutral position switch detects whether the shift position is in P position or in another position,
and sends a signal to the ECU.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

SR–94

–

STEERING

STEERING COLUMN