Lexus RX300 (MCU15). Service manual — part 250

DI–232

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300 (RM785E)

3

Check voltage between terminal SR of skid control ECU and body ground.

PREPARATION:
Remove the skid control ECU with connectors still connected.
CHECK:
Turn the ignition switch ON, measure between terminal SR and GND.
OK:

Voltage: 1V or less

NG

Check and repair harness or ABS solenoid
relay.

OK

If the same code is still output after the DTC is deleted, check the contact condition of each con-
nection. If the connections are normal, the ECU may be defective.

F05279

Battery

Fusible Link
Block
ABS

R/B No. 2

ABS
SOL Relay

ABS Motor Relay

Brake Actuator

2

3

W

B

2

2

2

2

2

1

5

3

2

3

W–L

W–B

A7

W–B

W–B

LG–B

B–W

GR

29

A21

MR

MT

Skid Control ECU

EA

ED

1

A21

R+

A21

28

A7

A7

1

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–233

LEXUS RX300 (RM785E)

DTC

C0273 / 13, C0274 / 14

ABS Motor Relay Circuit

CIRCUIT DESCRIPTION

The ABS motor relay supplies power to the ABS pump motor. While the ABS & BA & TRC & VSC are acti-
vated, the ECU switches the motor relay ON and operates the ABS pump motor.

DTC No.

DTC Detecting Condition

Trouble Area

C0273 / 13

Conditions 1. and 2. continued for 0.2 sec. or more:

1. ECU terminal IG1 voltage is 9.5 V to 17.2 V in the initial

check or ABS, TRC or VSC are in operation, and when

the motor relay is ON, however the contact point of the

motor relay is OFF.

2. ECU terminal IG1 is 9.5 V or less, and when the motor

relay is ON, but the contact point of the motor relay does

not become ON.

S ABS motor relay

S ABS motor relay circuit

C0274 / 14

When the motor relay is OFF, the condition that the contact

point of motor relay is ON continues for 4 sec. or more.

WIRING DIAGRAM

DI1GJ–08

F12363

(+)

(–)

R/B No. 2

1

DI–234

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300 (RM785E)

INSPECTION PROCEDURE

HINT:
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.

1

Check ABS motor relay operation.

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 the operation sound of the ABS motor relay when operating it with the hand–held tester.
OK:

The operation sound of the ABS motor relay should be heard.

OK

Go to step 4.

NG

2

Check voltage between terminal 1 of R/B No. 2 (for ABS motor relay) and body
ground.

PREPARATION:
Remove the ABS motor relay from R/B No. 2.
CHECK:
Measure voltage between terminal 1 of R/B No. 2 (for ABS mo-
tor relay) and body ground.
OK:

Voltage: 10 – 14 V

NG

Check and repair harness or connector.

OK

F00044

1

2

3

4

(+)

(–)

Continuity

1

2

3

4

1

2

3

4

Open

Continuity

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–235

LEXUS RX300 (RM785E)

3

Check ABS motor relay.

CHECK:
Check continuity between each pair of terminal of motor relay.
OK:

Terminals 3 and 4

Continuity

(Reference value 62 Ω)

Terminals 1 and 2

Open

CHECK:
(a)

Apply battery voltage between terminals 3 and 4.

(b)

Check continuity between terminals.

OK:

Terminals 1 and 2

Continuity

NG

Replace ABS motor relay.

OK