Lexus ES300 (2002 year). Manual - part 355

A53763

E2

THA

A54406

E10

05-40

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

193

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

3

READ VALUE OF OBD II SCAN TOOL OR HAND-HELD TESTER(CHECK FOR
OPEN)

(a)

Connect the terminals THA with E2 of the ECM connector.

HINT:
Before checking, do a visual check and connector connection
inspection of the ECM.
(b)

Read temperature value on the hand-held tester.
Temperature: 140

°

C (284

°

F) or more

OK

CHECK AND REPLACE HARNESS AND
CONNECTOR

NG

CHECK AND REPLACE ECM

4

READ VALUE OF OBD II SCAN TOOL OR HAND-HELD TESTER(CHECK FOR
SHORT)

(a)

Disconnect the intake air flow meter connector.

(b)

Turn the ignition switch ON.

(c)

Read temperature value on the hand-held tester.
Temperature: -40



C (-40



F)

OK

REPLACE INTAKE AIR FLOW METER
SUB-ASSY

NG

5

READ VALUE OF OBD II SCAN TOOL OR HAND-HELD TESTER(CHECK FOR
SHORT)

(a)

Disconnect the ECM E10 connector.

(b)

Turn the ignition switch ON.

(c)

Read temperature value on the hand-held tester.
Temperature: -40

°

C (-40

°

F)

OK

REPAIR OR REPLACE HARNESS AND
CONNECTOR

NG

CHECK AND REPLACE ECM

A00310

A60786

G - B

BR

19

28

E10

E10

E2

THW

R

5V

E1

ECM

E.F.I. Engine Coolant Temp. Sensor

2

1

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-41

194

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

P0115

ENGINE COOLANT TEMP. CIRCUIT
MALFANCTION

CIRCUIT DESCRIPTION

A thermistor built into the water temp. sensor changes the resistance value according to the water tempera-
ture.
The structure of the sensor and connection to the ECM is the same as the ones of the air temperature sensor.
If the ECM detects the DTC P0115, it operates the fail-safe functions in which the engine coolant tempera-
ture is assumed to be 80



C (176



F).

DTC No.

DTC Detecting Condition

Trouble Area

P0115

Open or short in water temp. sensor circuit

Open or short in water temp. sensor circuit

E.F.I. engine coolant temperature sensor

ECM

HINT:
After confirming DTC P0115, use the OBD II scan tool or hand-held tester to confirm the engine coolant
temperature from the CURRENT DATA.

Temp. Displayed

Malfunction

-40



C (-40



F)

Open circuit

140



C (284



F) or more

Short circuit

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

If DTC P0110 (Intake Air Temp. Circuit Malfunction), P0115 (Water Temp. Circuit Malfunction), P0120
(Throttle/Pedal Position Sensor/Switch ”A” Malfunction) are output simultaneously, E1, E2 etc. (Sen-
sor Ground system) may be open.

Read freeze frame data using hand-held tester. Because freeze frame records the engine conditions
when the malfunction is detected, when troubleshooting it is useful for determining whether the vehicle
was running or stopped, the engine warmed up or not, the air-fuel ratio lean or rich, etc. at the time
of the malfunction.

051LX-08

1

2

A50582

A53763

THW

E2

05-42

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

195

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

1

READ VALUE OF OBD II SCAN TOOL OR HAND-HELD TESTER(COOLANT
TEMP/WATER TEMP)

(a)

Read temperature value on the hand-held tester.
Temperature: The same as actual water temperature
Result:

A

B

C

-40



C (-40



F)

140



C (284



F)

OK

B

Go to step 4

C

CHECK FOR INTERMITTENT PROBLEMS

A

2

READ VALUE OF OBD II SCAN TOOL OR HAND-HELD TESTER(CHECK FOR
OPEN)

SST

09843-18040

(a)

Disconnect the water temperature sensor connector.

(b)

Connect the terminals 1 with 2 of the water temperature
sensor connector.

(c)

Turn the ignition switch ON.

(d)

Read temperature value on the hand-held tester.
Temperature: 140

°

C (284

°

F) or more

OK

REPLACE E.F.I.  ENGINE COOLANT
TEMPERATURE SENSOR

NG

3

READ VALUE OF OBD II SCAN TOOL OR HAND-HELD TESTER(CHECK FOR
OPEN)

(a)

Connect the terminals THW with E2 of the ECM connec-
tor.

(b)

Turn the ignition switch ON.

(c)

Read temperature value on the hand-held tester.
Temperature: 140

°

C (284

°

F) or more

OK

REPAIR OR REPLACE HARNESS AND
CONNECTOR

NG

CHECK AND REPLACE ECM

A54406

E10

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-43

196

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

4

READ VALUE OF OBD II SCAN TOOL OR HAND-HELD TESTER(CHECK FOR
SHORT)

(a)

Disconnect the water temp. sensor connector.

(b)

Turn the ignition switch ON.

(c)

Read temperature value on the hand-held tester.
Temperature: -40

°

C (-40

°

F)

OK

REPLACE E.F.I.  ENGINE COOLANT
TEMPERATURE SENSOR

NG

5

READ VALUE OF OBD II SCAN TOOL OR HAND-HELD TESTER(CHECK FOR
SHORT)

(a)

Disconnect the ECM E10 connector.

(b)

Turn the ignition switch ON.

(c)

Read temperature value on the hand-held tester.
Temperature: -40

°

C (-40

°

F)

OK

REPAIR OR REPLACE HARNESS AND
CONNECTOR

NG

CHECK AND REPLACE ECM