Lexus RX300 (MCU15). Service manual - part 258

F05273

Instrument Panel J/B

ECU–IG Fuse

DI–264

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Check ECU–IG fuse.

PREPARATION:
Remove the ECU–IG fuse from instrument panel J/B.
CHECK:
Check continuity of ECU–IG fuse.
OK:

Continuity

NG

Check for short circuit in all the harness and
components connected to ECU–IG fuse (See
attached wiring diagram).

OK

2

Check battery voltage.

CHECK:
Check the battery voltage.
OK:

Voltage: 10 – 14 V

NG

Check and repair the charging system (See 
page CH–2).

OK

GND4

F09165

ON

GND1

GND2

IG1

GND3

(+)

(–)

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–265

LEXUS RX300   (RM785E)

3

Check voltage of the ECU–IG power source.

In case of using the hand–held tester:
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 DATALIST mode on the hand–held tester.

CHECK:
Check the voltage condition output from the ECU displayed on the hand–held tester.
OK:

”Normal” is displayed.

In case of not using the hand–held tester:
PREPARATION:
Remove the skid contol ECU with connectors still connected.
CHECK:
Turn the ignition switch ON, measure voltage between termi-
nals IG1 and GND of skid control ECU connector.
OK:

Voltage: 10 – 14 V

OK

Check and replace skid control ECU.

NG

F02836

GND1

GND2

GND3

GND4

DI–266

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300   (RM785E)

4

Check continuity between terminal GND of skid control ECU connector and body
ground.

CHECK:
Measure resistance between terminals GND of skid control
ECU connector and body ground.
OK:

Resistance: 1 Ω or less

NG

Repair or replace harness or connector.

OK

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

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–267

LEXUS RX300   (RM785E)

DTC

C1243 / 43, C1245 / 45

Malfunction in Deceleration Sensor

CIRCUIT DESCRIPTION

DTC No.

DTC Detecting Condition

Trouble Area

C1243 / 43

While vehicle speed gets to 0 km/h (0 mph) from 30 km/h (18

mph), and the condition that GL1 and GL2 signals of ECU

terminals did not change 2 LSB or more continued in a 

sequence 16 times.

Deceleration sensor

C1245 / 45

At the vehicle speed of 30 km/h (18 mph) or more, and the

condition that the difference between acceleration and decel-

eration values of computation from deceleration sensor and

vehicle speed becomes more than 0.35 G continues for 60

sec. or more.

S Deceleration sensor

S Wire harness for deceleration sensor system

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 the hand–held tester.

1

Check output value of the deceleration sensor.

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 DATALIST mode on the hand–held tester.

CHECK:
Check that the deceleration value of the deceleration sensor displayed by the hand–held tester is changing
when tilting the vehicle.
OK:

Deceleration value must be changing.

OK

Check and replace skid control ECU.

NG

2

Check deceleration sensor (See page DI–205).

NG

Replace deceleration sensor.

OK

DI1GL–05