Lexus ES300 (2002 year). Service manual — part 354

05-2

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

155

2002 LEXUS ES300 REPAIR MANUAL (RM911U)

9

SYMPTOM SIMULATION

10

DTC CHECK (See page

05-5

)

A

Malfunction code

B

No code

B

GO TO STEP 12

A

11

DTC CHART (See page

05-18

)

GO TO STEP 14

12

BASIC INSPECTION (See page

05-5

)

A

Not confirm wrong parts

B

Confirm wrong parts

B

GO TO STEP 17

A

13

PROBLEM SYMPTOMS TABLE (See page

05-30

)

A

Confirm wrong circuit

B

Confirm wrong Parts

B

GO TO STEP 17

A

14

CHECK ECM POWER SOURCE CIRCUIT (See page

05-178

)

15

CIRCUIT INSPECTION

A

Not confirm malfunction

B

Confirm malfunction

B

GO TO STEP 18

A

16

CHECK FOR INTERMITTENT PROBLEMS (See page

05-5

)

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-3

156

2002 LEXUS ES300 REPAIR MANUAL (RM911U)

GO TO STEP 18

17

PARTS INSPECTION

18

IDENTIFICATION OF PROBLEM

19

ADJUSTMENT, REPAIR

20

CONFIRMATION TEST

END

(fig. 1)

Acceptable

Resistance k

Ω

- 20

0

20

40

60

80

100

(- 4)

32

68

104

140

176

212

30

20

10

5

3

2

1

0.5

0.3

0.2

0.1

Temp.

°

C (

°

F)

FI4741

A00310

A60786

Intake Air Temp. Sensor
(Inside Intake Air Flow Meter)

4

5

L - B

BR

20

28

E10

E10

E2

THA

R

5V

E1

ECM

05-38

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

191

2002 LEXUS ES300 REPAIR MANUAL (RM911U)

DTC

P0110

INTAKE AIR TEMP. CIRCUIT MALFUNCTION

CIRCUIT DESCRIPTION

The intake air temp. sensor is built into the air flow meter and
senses the intake air temperature.
A thermistor built in the sensor changes the resistance value
according to the intake air temperature.
The lower the intake air temperature, the greater the thermistor
resistance value, and the higher the intake air temperature, the
lower the thermistor resistance value (See fig. 1).
The intake air temp. sensor is connected to the engine ECM
(See below ). The 5 V power source voltage in the engine ECM
is applied to the intake air temp. sensor from the terminal THA
via resistor R.
That is, the resistor R and the intake air temp. sensor are con-
nected in series. When the resistance value of the intake air
temp. sensor changes in accordance with changes in the intake
air temperature, the potential at terminal THA also changes.
Based on this signal, the engine ECM increases the fuel injec-
tion volume to improve driveability during cold engine opera-
tion.
If the ECM detects the DTC P0110, it operates the fail-safe
function in which the intake air temperature is assumed to be
20

C (68

F).

DTC No.

DTC Detecting Condition

Trouble Area

P0110

Open or short in intake air temp. sensor circuit

Open or short in intake air temp. sensor circuit

Intake air temp. sensor (Inside intake air flow meter)

ECM

WIRING DIAGRAM

051LW-06

A54396

E2

THA

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-39

192

2002 LEXUS ES300 REPAIR MANUAL (RM911U)

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, E2 (Sensor
Ground) 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.

1

READ VALUE OF OBD II SCAN TOOL OR HAND-HELD TESTER(INAKE AIR)

(a)

Read temperature value on the hand-held tester.
Temperature: The same as actual intake air temperature
Resistance:

A

B

C

-40

°

C (-40

°F

)

140

°

C (284

°F

) or more

OK

B

Go to step 4

C

GO TO RELEVANT DTC CHART

A

2

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

SST

09843-18040

(a)

Disconnect the intake air flow meter connector.

(b)

Connect the terminal THA with E2.

(c)

Turn the ignition switch ON.

(d)

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

°

C (284

°

F) or more

OK

REPLACE INTAKE AIR FLOW METER
SUB-ASSY

NG