Lexus RX300 (MCU15). Manual — part 207

B02101
B04941

A06102

1.1 mm

DI–60

–

DIAGNOSTICS

ENGINE

LEXUS RX300 (RM785E)

1

Check wire harness, connector and vacuum hose in engine room.

CHECK:
(a)

Check the connection conditions of wire harness and connector.

(b)

Check the disconnection, piping and break or vacuum hose.

NG

Repair or replace, then confirm that there is no
misfire (See confirmation driving pattern).

OK

2

Check spark plug and spark of misfiring cylinder.

PREPARATION:
Remove the spark plug (See page IG–1).
CHECK:
(a)

Check the electrode of carbon deposits electrode.

(b)

Check the electrode gap.

OK:

(a) No large carbon deposit present.
Not wet with gasoline or oil.
(b) Electrode gap: 1.1 mm (0.043 in.)

PREPARATION:
(a)

Install the spark plug to the ignition coil.

(b)

Disconnect the injector connector.

(c)

Ground the spark plug.

CHECK:
Check if spark occurs while the engine is being cracked.
NOTICE:
To prevent excess fuel being injected from the injectors
during this test, don’t crank the engine for more than 5 – 10
seconds at a time.
OK:

Spark jumps across electrode gap.

NG

Replace or check ignition system (See page
IG–1).

OK

A02024

ON

#10

(+)

(–)

#20

#30

#40

#50

#60

FI6588 FI6538

A00064

10 V/
Division

GND

10 V/
Division

100 msec./Division (Idling)

GND

(Magnification)

1 msec./Division (Idling)

Injection duration

Injector Signal Waveform

–

DIAGNOSTICS

ENGINE

DI–61

LEXUS RX300 (RM785E)

3

Check voltage of engine ECU terminals for injector of failed cylinder.

PREPARATION:
(a)

Remove the engine ECU with connector still connected
(See page FI–70).

(b)

Turn the ignition switch ON.

CHECK:
Measure voltage between applicable terminal of the engine
ECU connector and body ground.
OK:

Voltage: 9 – 14 V

Reference: INSPECTION USING OSCILLOSCOPE
With the engine idling, measure between terminals #10 – #40 and E01 of the engine ECU connector.
HINT:
The correct waveforms are as shown.

OK

Go to step 4.

NG

DI–62

–

DIAGNOSTICS

ENGINE

LEXUS RX300 (RM785E)

4

Check resistance of injector of misfiring cylinder (See page FI–18).

NG

Replace injector.

OK

Check for open and short in harness and con-
nector between injector and engine ECU (See
page IN–32).

5

Check fuel pressure (See page FI–5).

NG

Check and repair fuel pump, pressure regulator,
fuel pipe line and filter (See page FI–1).

OK

6

Check injector injection (See page FI–22).

NG

Replace injector.

OK

7

Check mass air flow meter and water temp. sensor (See pages FI–30 and
FI–63).

NG

Repair or replace.

OK

Check compression pressure, valve clear-
ance and valve timing.

A03315

Knock Sensor 1
(on Right Bank)

Knock Sensor 2
(on Left Bank)

EA1

1

1

W

W

1

2

W

B

E8

Engine ECU

27

28

KNKR

KNKL

E1

E1

EA1

E8

–

DIAGNOSTICS

ENGINE

DI–63

LEXUS RX300 (RM785E)

DTC

P0325

Knock Sensor 1 Circuit Malfunction (Bank 1)

DTC

P0330

Knock Sensor 2 Circuit Malfunction (bank 2)

CIRCUIT DESCRIPTION

Each of knock sensor is fitted to the right bank and left bank of the cylinder block to detect engine knocking.
This sensor contains a piezoelectric element which generates a voltage when it becomes deformed, which
occurs when the cylinder block vibrates due to knocking. If engine knocking occurs, ignition timing is retarded
to suppress it.

DTC No.

DTC Detecting Condition

Trouble Area

P0325

No knock sensor 1 signal to engine ECU with engine speed

between 2,000 rpm and 5,600 rpm

S Open or short in knock sensor 1 circuit

S Knock sensor 1 (looseness)

S Engine ECU

P0330

No knock sensor 2 signal to engine ECU with engine speed

between 2,000 rpm and 5,600 rpm

S Open or short in knock sensor 2 circuit

S Knock sensor 2 (looseness)

S Engine ECU

If the ECM detects the above diagnosis conditions, it operates the fail–safe function in which the corrective
retard angle value is set to the maximum value.

WIRING DIAGRAM

DI4EA–14