Lexus ES300 (2002 year). Service manual - part 356

05-44

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

197

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

P0116

ENGINE COOLANT TEMP.CIRCUIT
RANGE/PERFORMANCE PROBLEM

CIRCUIT DESCRIPTION

Refer to DTC P0115 on page 

05-41

.

DTC No.

DTC Detecting Condition

Trouble Area

If THW < -7



C (19.4



F), 20 min. or more after starting engine,

E.F.I. engine coolant temp. sensor value is 20



C (68



F) or less

(2 trip detection logic)

If THW 



 -7



C (19.4



F), and < 10



C (50



F), 5 min. or more

after starting engine, E.F.I. engine coolant temp. sensor value
is 20



C (68



F) or less (2 trip detection logic)

If THW 



 10



C (50



F), 2 min. or more after starting engine,

E.F.I. engine coolant temp. sensor value is 30



C (86



F) or less

(2 trip detection logic)

Cooling system

P0116

When THW 



 35



C (95



F) or more and less than 60



C

(140



F), and THA 

 

-6.7



C (19.9



F) or more, when starting

engine, conditions (a) and (b) continue: (2 trip detection logic)

(a) Vehicle speed is changing (Not stable)

(b) THW change is lower than 3



C (37.4



F) from THW since

when starting engine

Cooling system

E.F.I.engine coolant temperature sensor

In case that reading value of water temp. sensor will not
change more than 1



C (33.8



F) even after repeating 6 trips

(detection logic) of adjusting speed pattern with THW more
than 60



C (140



F) when engine starts.

INSPECTION PROCEDURE

HINT:

If DTCs P0115 and P0116 are output simultaneously, E.F.I. engine coolant temperature sensor circuit
may be open. Perform troubleshooting of DTC P0115 first.

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

1

CHECK OTHER DTC OUTPUT(BESIDES DTC P0116)

(a)

Read the DTC using the hand-held tester or OBD II scan tool.

YES

GO TO RELEVANT DTC CHART

NO

2

INSPECT THERMOSTAT (See page 

16-2

)

NG

REPLACE THERMOSTAT

OK

REPLACE E.F.I.  ENGINE COOLANT TEMPERATURE SENSOR

051LY-07

A02396

A02395

A02624

Throttle Position Sensor 

Output V

oltage (V)

0

1.5

Throttle Valve Opening Angle (deg)

70

125

VTA1

VTA2

5

VTA2 VTA1

E2

VC

Movable Range

Usable Range

Usable Range

*

1

*

2

*

1

*

2

Movable Range

Usable
Range

*

2

*

1

Accelerator pedal

released (15

°

)

Accelerator pedal

depressed (about

100

°

)

*

2

:

*

1

:

VTA2 circuit open or ground short

Accelerator pedal position expressed as percentage and voltage

Accelerator pedal released

Accelerator pedal depressed

THROTTLE POS

THROTTLE POS #2

THROTTLE POS

THROTTLE POS #2

0 %

0 %

100 %

8 - 20 %

0 V

2.0 - 2.9 V

0 V

5 V

0 %

0 %

100 %

0 V

4.6 - 5.0 V

0 V

5 V

Trouble area

VC circuit open

VTA1 circuit open or ground short

E2 circuit open

64 - 96 %

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DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-45

198

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

P0120

THROTTLE PEDAL POSITION
SENSOR/SWITCH ”A” CIRCUIT
MALFUNCTION

CIRCUIT DESCRIPTION

Throttle position sensor is mounted on the throttle body and it has 2 sensors to detect the throttle opening
angle and the malfunction of the throttle position sensor’s own.
The voltage applied to terminals VTA1 and VTA2 of the ECM changes between 0 V and 5 V in proportion
to the opening angle of the throttle valve.
The ECM judges the current opening angle of the throttle valve from these signals input from terminals VTA1
and VTA2, and the ECM controls the throttle motor to make the throttle valve angle properly in response to
the driving condition.
If this DTC is stored, the ECM cuts the power down for the throttle motor, and the throttle valve is fully closed
by the return spring.

DTC No.

DTC Detection Condition

Trouble Area

P0120

Condition (a), (b), (c), (d) or (e) continues for 2.0 seconds: 

(IDL ON: 10 seconds)

(a) VTA1 

 0.2 V

(b) VTA2 

 0.5 V

(c) VTA1 



 4.8 V

(d) When VTA 



 0.2 V and 

 1.8 V, and VTA2 



 4.97 V

(e) VTA1-VT A2 

 0.02 V

(f) IDL is OFF

Open or short in throttle position sensor circuit

Throttle body assy (Throttle position sensor)

ECM

Condition (a) continues for 0.4 seconds:

(a) VTA1 

 0.2 V and VTA2 

 0.5 V

HINT:
After confirming DTC P0120, use the OBD II scan tool or hand-held tester to confirm the throttle valve open-
ing percentage and closed throttle position switch condition.

055C5-03

A54267

T3
Throttle Position Sensor

ECM

2

1

3

4

LG

Y

B-R

BR

21

18

31

28

E10

E10

E10

E10

5 V

VTA1

VC

VTA2

E2

FI7052

05-46

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DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

199

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

WIRING DIAGRAM

INSPECTION PROCEDURE

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

Hand-held  tester:

1

READ VALUE OF HAND-HELD TESTER(THROTTLE VALVE OPENING
PERCENTAGE)

(a)

Read the throttle valve opening percentage for the VTA
circuit and read the voltage for the VTA2 circuit.

Accelerator pedal

Throttle valve opening

position expressed 

as percentage (VTA1)

Voltage

(VTA2)

Released

8 - 20 %

2.0 - 2.9 V

Depressed

64 - 96 %

4.6 - 5.0 V

HINT:
If the throttle position is 100 % when releasing throttle pedal,
ETA1 circuit is open.
If the throttle position is 0 % when depressing accelerator ped-
al, VC or VTA1 circuit is open.
If  the throttle position is not 0 % when releasing accelerator
pedal or throttle position is not 100 % when depressing throttle
pedal, VTA2 circuit is open or short.

OK

CHECK FOR INTERMITTENT PROBLEMS
(See page 

01-31

)

NG

A53763

E2

VC

A53763

VTA1

E2

VTA2

A54410

E2

VC

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-47

200

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

2

INSPECT ECM(VC - E2)

(a)

Measure the voltage between terminals VC and E2 of the
ECM connector.
Voltage: 4.5 - 5.5 V

NG

CHECK AND REPLACE ECM

OK

3

INSPECT ECM(VTA1 - E2, VTA2 - E2)

(a)

Measure the voltage between terminals VTA1 and E2,
and VTA2 and E2 of the ECM connector.

A

l

t

d l

Voltage

Accelerator pedal

VTA1 - E2

VTA2 - E2

Released

0.4 - 1.0 V

2.0 - 2.9 V

Depressed

3.2 - 4.8 V

4.6 - 5.0 V

NG

CHECK AND REPLACE ECM

NG

4

INSPECT E.F.I. THROTTLE POSITION SENSOR

(a)

Disconnect the throttle position sensor connector.

(b)

Using an ohmmeter, measure the resistance between ter-
minals VC and E2.
Resistance: 1.2 - 3.2 k

Ω

 at 20

°

C (68

°

F)

NG

REPLACE E.F.I. THROTTLE POSITION SENSOR
(See page 

10-6

)

OK