Lexus ES300 (1997 year). Service manual — part 323

–

DIAGNOSTICS

ENGINE

DI–69

221

1997 LEXUS ES300 (RM511U)

DTC

P0340

Camshaft Position Sensor Circuit
Malfunction

CIRCUIT DESCRIPTION

Camshaft position sensor (G22 signal) consist of a signal plate and pickup coil.
The G22 signal plate has one tooth, on its outer circumference and is mounted on the left bank camshafts.
When the camshafts rotate, the protrusion on the signal plate and the air gap on the pickup coil change,
causing fluctuations in the magnetic field and generating an electromotive force in the pickup coil.
The NE signal plate has 34 teeth and is mounted on the crankshaft. The NE signal sensor generates 34
signals for every engine revolution. The ECM detects the standard crankshaft angle based on the G22 signal
and the actual crankshaft angle and the engine speed by the NE signals.

DTC No.

DTC Detecting Condition

Trouble Area

P0340

No camshaft position sensor signal to ECM during cranking

(2 trip detection logic)

Open or short in camshaft position sensor circuit

Camshaft position sensor

P0340

No camshaft position sensor signal to ECM with engine speed

600 rpm or more

Camshaft osition sensor

Starter

ECM

WIRING DIAGRAM

Refer to DTC P0335 on page

DI–66

for the WIRING DIAGRAM.

INSPECTION PROCEDURE

1

Check resistance of camshaft position sensor (See page

IG–1

).

Reference INSPECTION USING OSCILLOSCOPE
Refer to DTC P0335 on page

DI–66

for the OSCILLOSCOPE.

NG

Replace camshaft position sensor.

OK

2

Check for open and short in harness and connector between ECM and camshaft
position sensor (See page

IN–27

).

NG

Repair or replace harness or connector.

OK

DI09R–01

DI–70

–

DIAGNOSTICS

ENGINE

222

1997 LEXUS ES300 (RM511U)

3

Inspect sensor installation and tooth of left bank camshaft timing pulley.

NG

Tighten the sensor.
Replace left bank camshaft timing pulley.

OK

Check and replace ECM (See page

IN–27

).

A00199

ECM

Mass Air Flow Meter

VSV
for
EGR

EGR Valve
Position
Sensor

EGR Valve

EGR Gas
Temp. Sensor

Crankshaft Position Sensor

Engine Coolant
Temp. Sensor

Intake Air
Chamber

Throttle Valve

Vacuum
Control
Valve

–

DIAGNOSTICS

ENGINE

DI–71

223

1997 LEXUS ES300 (RM511U)

DTC

P0401

Exhaust Gas Recirculation Flow
Insufficient Detected

CIRCUIT DESCRIPTION

The EGR system recirculates exhaust gas, which is controlled to the proper quantity to suit the driving condi-
tions, into the intake air mixture to slow down combustion, reduce the combustion temperature and reduce
NOx emissions.
The lift amount of EGR valve is controlled by the vacuum which is regulated by the Duty–VSV operated by
the ECM. The lift amount of EGR valve is detected by the EGR valve position sensor which is mounted on
the EGR valve and it provides feedback to the ECM to control the lift amount of EGR valve in response to
engine operating conditions.
Under the following conditions, EGR is cut to maintain driveability.

Before the engine is warmed up

During deceleration (throttle valve closed)

Light engine load (amount of intake air very small)

Engine speed over 4,000 rpm

Engine idling

DI09S–01

S05714

Junction
Connector

J23
Junction
Connector

From FL MAIN

From
Ignition Switch

Engine Room J/B

EFI Relay

EFI

2A

2K

2J

2F

1

7

5

1

3
2

2

4

B–Y

B

B

B–Y

J28

J29

W–B

EC

IK3

9

B–Y

B–Y

EGR Gas Temp. Sensor

VSV for EGR

Y–G

A

A 1

2

E8

12

E8

E9

15

22

1

2

G–Y

BR

ECM

EGR

E01

EGLS

5V

E2

EGR Valve Position Sensor

3

E9

1

VC

5V

THG

E2

E1

E8

E9

22

14

2

1

W–G

Y

BR

DI–72

–

DIAGNOSTICS

ENGINE

224

1997 LEXUS ES300 (RM511U)

DTC No.

DTC Detecting Condition

Trouble Area

P0401

After the engine is warmed up and run at 80 km/h (50 mph) for

3 to 5 min. the EGR gas temperature sensor valve does not

exceed 35

°C (95°F) above the ambient air temperature

(2 trip detection logic)

EGR valve (stuck closed)

Open or short in EGR gas temp. sensor circuit

EGR gas temp. sensor

Open in VSV circuit for EGR

VSV for EGR

Vacuum control valve

Vacuum hose disconnected or blocked

ECM

WIRING DIAGRAM