Lexus SC300 / Lexus SC400. Service manual - part 771

LOCATION OF CONNECTORS IN SEAT

–

STEERING

STEERING COLUMN

SR–61

SR–52

).

IN–33

).

WIRING DIAGRAM

CIRCUIT INSPECTION

ECU Power Source Circuit

CIRCUIT DESCRIPTION

The ECU power source also supplies power to the CPU and sensor, etc. Power is supplied to the ECU even
when the ignition switch is off.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

SR–62

–

STEERING

STEERING COLUMN

NG

OK

OK

NG

INSPECTION PROCEDURE

1

Check voltage between terminals ECU–B and ECU–E of ECU connector.

C

OK

P

Remove ECU with connectors still connected.

Measure voltage between terminals ECU–B and ECU–
E of ECU connector.

Voltage:

10 ~ 14 V

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

SR–52

).

2

Check continuity between terminal ECU–E of ECU connector and body ground.

C

OK

Measure resistance between terminal ECU–E of ECU
connector and body ground.

Resistance:

1 

 or less

Repair or replace harness or connector.

Go to Step 

.

–

STEERING

STEERING COLUMN

SR–63

OK

NG

3

Check DOME Fuse.

C

OK

P

Remove DOME Fuse from R/B No. 2.

Check continuity of DOME Fuse.

Continuity

Check for short in all the harness and components con-
nected to DOME Fuse (See attached wiring diagram).

Check harness and connector between ECU and
battery (See page 

IN–33

).

SR–64

–

STEERING

STEERING COLUMN