Lexus RX300 (MCU15). Service manual - part 252

F00042

1

3

4

6

Open

(+)

(–)

1

2

3

4

4

5

6

1

2

3

2

5

6

5

Continuity

Continuity

Continuity

Open

DI–240

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300   (RM785E)

3

Check ABS solenoid relay.

CHECK:
Check continuity between each terminal of ABS solenoid relay.
OK:

Terminals 4 and 6

Continuity

(Reference value 80 Ω)

Terminals 2 and 3

Continuity

Terminals 1 and 3

Open

CHECK:
(a)

Apply battery voltage between terminals 4 and 6.

(b)

Check continuity between each terminal of ABS solenoid
relay.

OK:

Terminals 2 and 3

Open

Terminals 1 and 3

Continuity

NG

Replace ABS solenoid relay.

OK

F07134

ABS Solenoid 

Relay

3

5

5

6

ECU

R/B No. 2

A20

A7

4

4

A7

Brake Actuator

AST

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–241

LEXUS RX300   (RM785E)

4

Check continuity between terminals 3 of ABS solenoid relay and each solenoid
terminal of skid control ECU.

CHECK:
Check continuity between terminal 3 of R/B No. 2 (for ABS sole-
noid relay) and terminal AST of skid control ECU
OK:

Continuity

HINT:
There is a resistance of 26 – 40 Ω between terminals A7 – 4 and
A7 – 5 of brake actuator.

NG

Repair or replace harness or brake actuator.

OK

5

Check for open and short circuit in harness and connector between ABS sole-
noid relay and skid control ECU (See page IN–32).

NG 

Repair or replace harness or connector.

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.

DI–242

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300   (RM785E)

DTC

C1201 / 51

Engine Control System Malfunction

CIRCUIT DESCRIPTION

If any trouble occurs in the engine control system, the ECU prohibits BA & TRC & VSC control.

DTC No.

DTC Detecting Condition

Trouble Area

C1201 / 51

The engine speed is 500 rpm or more and ENG malfunction

signal continuously occurs for 5 sec. or more.

Engine control system

INSPECTION PROCEDURE

1

Check the DTC for the engine (See page DI–3).

*1

Repair engine control system according to the
code output.

*2

Check for engine and ECT ECU connected to
malfunction indicator light.

*1: Output NG code
*2: Malfunction indicator light remains ON

DI1GY–09

F13426

18

Instrument Panel J/B

22

Brake 
Warning Light

Combination
Meter

Brake Fluid Level
Warning Switch

Skid Control ECU

LBL

J9
Junction 
Connector

IJ1

II1

A

2

A23

C10

B–Y

BRL

1

1

W–L

AM1

W–B

A23

11

R–W (*2)

G

R–W

C12

1

R–W

HEATER

5

7

2

4

Ignition Switch

1C

6

2

1

Instrument Panel J/B

*1 : LHD 
*2 : RHD

G

J/B No. 3

1

3E

3A

13
1K

1C

14

9

1D

1B

W–B

R–W (*2)

26

R–W (*1)

IG

Instrument Panel J/B

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–243

LEXUS RX300   (RM785E)

DTC

C1202 / 52

Brake Fluid Level Warning Switch 
Circuit

CIRCUIT DESCRIPTION

The brake fluid level warning switch sends the appropriate signal to the ECU when the brake fluid level drops.
HINT:
Depress the parking brake pedal and also turns on the brake warning light but does not diagnose DTC No.
C1202 / 52.

DTC No.

DTC Detecting Condition

Trouble Area

C1202 / 52

ECU terminal IG1 voltage is 9.5 V to 17.2 V and open cir-

cuit for the brake fluid level warning switch circuit continues

for 2 sec. or more.

S Brake fluid level

S Brake fluid level warning switch

S Brake fluid level warning switch circuit

WIRING DIAGRAM

DI1GZ–11