Lexus RX300 (MCU15). Service manual - part 264

DI–288

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DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

HINT:
Troubleshoot in accordance with the chart below for each trouble symptom.

ABS warning light does not light up

*1

ABS warning light remains on

*2

*1: Start the inspection from step 1 in case of using the hand–held tester and start from step 2 in case of
      not using hand–held tester.
*2: After inspection of step 3, start the inspection from step 4 in case of using the hand–held tester and start
      from step 5 in case of not using hand–held tester.

1

Check operation of the ABS warning light.

PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Turn the ignition switch ON and push the hand–held tester main switch ON.

(c)

Select the ACTIVE TEST mode on the hand–held tester.

CHECK:
Check that ”ON” of the ABS warning light can be shown on the combination meter using the hand–held tes-
ter.

OK

Check and replace skid control ECU.

NG

2

Check ABS warning light.

See combination meter troubleshooting on page BE–2.

NG

Repair bulb or combination meter assembly.

OK

3

Check that the ECU connectors are securely connected to the skid control ECU.

NO

Connect the connector to the skid control ECU.

YES

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–289

LEXUS RX300   (RM785E)

Check for open circuit in harness and connector between combination meter and skid control
ECU (See page IN–32).

4

Check operation of the ABS warning light (See step 1).

OK

Check and replace skid control ECU.

NG

5

Is DTC output?

Check DTC on page DI–205.

YES

Repair circuit indicated by the output code.

NO

Check for short circuit in harness and connector between DLC3 and skid control ECU (See page
IN–32).

F13434

Combination Meter

A23 LBL

11

A23

1

R–W

C10

22

1

C12

1

Ignition Switch

AM1

6

2

1

2

9

B–Y

1C

7

3E

5

W–L

A

IG

Brake Fluid Level
Warning Switch

2

4

IJ1

18

A22

15

PKB

Parking
Brake
Switch

Brake 
Warning Light

G

G

J/B No.3

BRL

Skid Control ECU

3A

R–W

1K

13

HEATER

Instrument Panel J/B

1

1C

Instrument Panel J/B

Instrument Panel J/B

J9
Junction
Connector

W–B

W–B

1B

1D

14

R–W (*1)

II1

26

R–W (*2)

R–W (*2)

R–L

R–W

J/B No.5

6

5A

3

5E

1

*1 : LHD
*2 : RHD

DI–290

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DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300   (RM785E)

Brake Warning Light Circuit

CIRCUIT DESCRIPTION

The brake warning light lights up when the brake fluid is insufficient, the parking brake is applied or the EBD
is defective.

WIRING DIAGRAM

DI6QP–07

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DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–291

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Check parking brake switch circuit (See page BE–2).

NG

Repair or replace parking brake switch circuit.

OK

2

Check brake fluid level warning switch circuit (See page BE–2).

NG

Repair or replace brake fluid level warning
switch circuit.

OK

3

Is DTC output for ABS?

Check DTC on page DI–205.

YES

Repair circuit indicated by the output code.

NO

4

Check brake warning light.

See combination meter troubleshooting on page BE–2.

NG

Repair or replace combination meter.

OK

Check and replace Skid control ECU.