Lexus ES300 (1997 year). Manual - part 321

–

DIAGNOSTICS

ENGINE

DI–61

213

1997 LEXUS ES300   (RM511U)

5

Check injector injection (See page 

SF–20

).

NG

 Replace injector.

OK

6

Check EGR system (See page 

EC–7

).

NG

 Replace EGR system.

OK

7

Check mass air flow meter and engine coolant temp. sensor 
(See page 

SF–29

, 

SF–57

).

NG

 Repair or replace.

OK

Check compression pressure, valve
clearance and valve timing.

FI6610

Knock Sensor 1
(On right bank)

Knock Sensor 2
(On left bank)

EC1

1

1

W

W

1

2

W

W

E9

E9

ECM

15

14

KNKR

KNKL

E1

E1

EC1

DI–62

–

DIAGNOSTICS

ENGINE

214

1997 LEXUS ES300   (RM511U)

DTC

P0325

Knock Sensor 1 Circuit Malfunction

DTC

P0330

Knock Sensor 2 Circuit Malfunction

CIRCUIT DESCRIPTION

Knock sensors are fitted one 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 ECM with engine speed between

2,000 rpm and 5,600 rpm

Open or short in knock sensor 1 circuit

Knock sensor 1 (looseness)

ECM

P0330

No knock sensor 2 signal to ECM with engine speed between

2,000 rpm and 5,600 rpm

Open or short in knock sensor 2 circuit

Knock sensor 2 (looseness)

ECM

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

DI09P–01

A00304

Knock Sensor

ECM

EC1

Male
Connector

Female
Connector

1

1

1 1

2 2

KNKR

KNKL

EC1

E9

E9

15

14

FI7050
S06024
S06025

–

DIAGNOSTICS

ENGINE

DI–63

215

1997 LEXUS ES300   (RM511U)

INSPECTION PROCEDURE

HINT:DTC P0325 is for the right bank knock sensor circuit. DTC P0330 is for the left bank knock sensor cir-
cuit.

1

Connect OBD II scan tool or LEXUS hand–held tester and check knock sensor
circuit.

PREPARATION:
(a)

Connect the OBD II scan tool or LEXUS hand–held tester
to the DLC3.

(b)

Disconnect the wire to wire connector EC1.

(c)

Connect the terminals of the disconnected EC1 male con-
nector and EC1 female as follows.

Male connector 

↔

Female connector

Terminal 1 

↔

 Terminal 2

Terminal 2 

↔

 Terminal 1

(d)

Turn ignition switch ON and switch the OBD II scan tool
or LEXUS hand–held tester main switch ON.

(e)

After the engine is warmed up, perform quick racing to
4,000 rpm three times.

CHECK:
Check the DTC.
RESULT:

Type I

DTC same as when vehicle brought in. 

P0325 

→

 P0325 or P0330 

→

 P0330

Type II

DTC different to when vehicle brought in. 

P0325 

→

 P0330 or P0330 

→

 P0325

Type II

 Go to step 3 .

Type I

DI–64

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DIAGNOSTICS

ENGINE

216

1997 LEXUS ES300   (RM511U)

2

Check for open and short in harness and connector between EC1 connector and
ECM (See page 

IN–27

).

NG

 Repair or replace harness or connector.

OK

Check and replace ECM (See page 

IN–27

).

3

Check for open and short in harness and connector between EC1 connector and
knock sensor (See page 

IN–27

).

HINT:

If DTC P0325 has changed to P0330, check the knock sensor circuit on the right bank side.

If DTC P0330 has changed to P0325, check the knock sensor circuit on the left bank side.

NG

 Repair or replace harness or connector.

OK

Replace knock sensor.