Lexus SC300 / Lexus SC400. Manual - part 279

WIRING DIAGRAM

ABS Warning Light Circuit

CIRCUIT DESCRIPTION

If the ECU detects trouble, it lights the ABS warning light while at the same time prohibiting ABS control.
At this time, the ECU records a diagnostic trouble code in memory.After removing the short pin of the DLC1,
connect a DLC1 or connect terminals Tc and E1 of the DLC2 to make the ABS warning light to blink and
output the diagnostic trouble code.DIAGNOSTIC CHARTPerform troubleshooting in accordance with the
chart below for each trouble symptom.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

Perform troubleshooting in accordance with the chart below for each trouble symptom.

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ABS warning light does not light up

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

Go to step 

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ABS warning light remains on

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

Go to step 

BR–144

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

BR–145

OK

NG

OK

NG

INSPECTION PROCEDURE

1

Check ABS warning light.

See Combination Meter Troubleshooting on page 

BE–159

.

Replace bulb or combination meter assembly.

2

Check ABS solenoid relay.

C

OK

P

OK

C

Remove solenoid relay from R/B No. 6.

Check continuity between each terminal of ABS sole-
noid relay shown below.

1.

Apply battery voltage between terminals 4 and 6.

2.

Check continuity between each terminal of ABS so-
lenoid relay shown below.

Replace ABS solenoid relay.

Repair or replace and check for open in harness and connector between check connector and ABS
solenoid relay and body ground (See page 

IN–33

).

BR–146

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

NO

YES

YES

NO

OK

NG

INSPECTION PROCEDURE

3

Is diagnosis trouble code output?

Perform diagnostic trouble code check on page 

BR–76

.

Repair circuit indicated by the code output.

4

Does ABS warning light go off if short pin is removed?

Check for short in harness and connector between warn-
ing light and data link connector 1 and ECU (See page

IN–33

).

5

Check ABS solenoid relay (See step 

No. 

).

Replace ABS solenoid relay.

Repair or replace and check for short in harness
and connector between data link connector 1 and
ABS solenoid relay (See page 

IN–33

).

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

BR–147