Lexus ES300 (2002 year). Manual - part 378

A59673

05-16

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

169

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

BASIC INSPECTION

When the malfunction code is not confirmed in the DTC check, troubleshooting should be carried out in the
order for all possible circuits to be considered as the causes of the problems. In  many cases, by carrying
out the basic engine check shown in the following flow chart, the location  causing the problem can be found
quickly and efficiently. Therefore, using of this check is essential  in engine troubleshooting.

1

CHECK BATTERY VOLTAGE

NOTICE:
Carry out this check underthe engine stoppage condition.

OK

NG

Voltage

11V or more

Less than 11V

NG

CHARGE OR REPLACE BATTERY

OK

2

CHECK IF ENGINE IS CRANKED

NG

PROCEED TO PROBLEM SYMPTOMS TABLE
ON PAGE 

05-30

OK

3

CHECK IF ENGINE STARTS

NG

GO TO STEP 7

OK

4

CHECK AIR FILER

(a)

Visually check that the air filter is not excessively dirty or
oily.

NOTICE:
If necessary, clean the filter with compressed air. First blow
from inside thoroughly, then blow from outside of filter.

NG

REPAIR OR REPLACE

OK

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-17

170

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

5

CHECK IDLE SPEED (See page 

14-1

)

NG

PROCEED TO PROBLEM SYMPTOMS TABLE
ON PAGE 

05-30

OK

6

CHECK IGNITION TIMIMG (See page 

18-1

)

NG

PROCEED TO PAGE 

18-1

  AND CONTINUE TO

TROUBLESHOOT

OK

PROCEED TO PROBLEM SYMPTOMS TABLE
ON PAGE 

05-30

7

CHECK FUEL PRESSURE (See page 

11-4

)

NG

PROCEED TO PAGE 

11-4

 AND CONTINUE TO

TROUBLESHOOT

OK

8

CHECK FOR SPARK(See page 

18-1

)

NG

PROCEED TO PAGE 

18-1

 AND CONTINUE TO

TROUBLESHOOT

OK

PROCEED TO PROBLEM SYMPTOMS TABLE ON PAGE 

05-30

A54290

0

Accelerator Pedal  Opening Angle (deg)

125

VPA1

VPA2

5

Movable Range

Usable Range

Usable Range

*1

*1

*2

Movable Range

Usable
Range

*2

*1

Accelerator pedal
released (15

°

)

Accelerator pedal
depressed (about
100

°

)

Accelerator

 Pedal 

Position Sensor 

Output V

oltage (V)

VPA2

VPA1

EP2

VCP2

*

1

:

*

2

:

EP1

0.8

105

VCP1

*2

VPA2 circuit open or ground short

Accelerator pedal position expressed as voltage

Accelerator pedal released

Accelerator pedal depressed

ACCEL POS #1

0 V

0 V

0 V

0.9 - 2.3 V

0 V

5 V

0 V

3.4 - 5.0 V

0 V

5 V

Trouble area

VCcircuit open

VPA1 circuit open or ground short

E2 circuit open

ACCEL POS #2

ACCEL POS #1

ACCEL POS #2

0.5 - 1.1 V

5 V

0 V

0 V

3.0 - 4.6 V

5 V

05-120

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

273

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

P1120

ACCELERATOR PEDAL POSITION SENSOR
CIRCUIT MALFUNCTION

CIRCUIT DESCRIPTION

Accelerator pedal position sensor is mounted on the accelerator pedal bracket and it has 2 sensors to de-
tects the accelerator position and a malfunction of the accelerator position’s own.
The accelerator pedal position sensor is the voltage applied to the terminals VPA1 and VPA2 of the ECM
changes between 0 V and 5 V in proportion to the opening angle of the accelerator pedal.
The ECM judges the current opening angle of the accelerator pedal from these signals input from terminals
VPA1 and VPA2 and the ECM controls the throttle motor based on these signals.
If this DTC is stored, the ECM shuts down the power for the throttle motor, and the throttle valve is fully closed
by the return spring.

DTC No.

DTC Detecting Condition

Trouble Area

P1120

Condition (a), (b), (c), (d) or (e) continues for 0.5 seconds:

(IDL ON: 10 seconds)

(a) VPA1 

 0.2 V

(b) VPA2 

 0.5 V

(c) VPA1 



 4.8 V

(d) When VPA1 



 0.2 V and 

 3.45 V, and VPA2 



 4.8 V

(e) VPA1-VP A2 

 0.02 V

(f) IDL is OFF

Open or short in accelerator pedal position sensor circuit

Accelerator pedal position sensor

ECM

Condition (a) or (b) continues for 2.0 seconds:

(a) VPA1 

 0.2 V and VPA2 

 0.5 V

After confirming DTC P1120, use the OBD II scan tool or hand-held tester to confirm the throttle valve open-
ing percentage.

056H8-02

A53752

Accelerator Pedal
Position Sensor

VPA2

VPA1

EP1

VCP1

VCP2

2

5

3

6

1

4

EP2

E6

E6

E6

E6

E6

E6

23

22

28

26

29

27

ECM

VPA2

VPA

EPA

VCPA

EPA2

VCP2

B-R

W-R

LG

R

L-Y

LG-B

FI7052

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-121

274

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

(a)

Select the item ”ACCEL POS #1” and ”ACCEL POS #2”
in the DATA LIST and read its value displayed on the
hand-held  tester.

Accelerator pedal

VPA

VPA2

Released

0.5 - 1.1 V

0.9 - 2.3 V

Depressed

3.0 - 4.6 V

3.4 - 5.0 V

OK

CHECK AND REPLACE ECM

NG