Switch ”A” Circuit Malfunction

vehicle driving conditions from this signal input from terminal ... After confirming DTC P0120, use the OBD II scan tool or TOYOTA hand-held tester to confirm the ...
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DI-37 DIAGNOSTICS

-

ENGINE DI6V0-02

DTC

P0120

Throttle Position Sensor/Switch ”A” Circuit Malfunction

CIRCUIT DESCRIPTION

Throttle Position Sensor

The throttle position sensor is mounted in the throttle body and detects the throttle valve opening angle. When the throttle valve is fully closed, a voltage of approximately 0.3 - 0.8 V is applied to terminal VTA of the ECM. The voltage applied to the terminals VTA of the ECM increases in proportion to the opening angle of the throttle valve and becomes approximately 3.2 - 4.9 V when the throttle valve is fully opened. The ECM judges the vehicle driving conditions from this signal input from terminal VTA, and uses it as one of the conditions for deciding the airfuel ratio correction, power increase correction and fuel-cut control etc.

ECM VC VTA E2

P24296

DTC No.

P0120

DTC Detecting Condition

Trouble Area

Condition (a) or (b) continues with more than 5 sec.: (a) VTA < 0.1 V (b) VTA > 4.9 V

 Open or short in throttle position sensor circuit  Throttle position sensor  ECM

HINT: After confirming DTC P0120, use the OBD II scan tool or TOYOTA hand-held tester to confirm the throttle valve opening percentage. Throttle valve opening position expressed as percentage

Trouble Area

Throttle valve fully closed

Throttle valve fully open

0%

0%

VC line open VTA line open or short

Approx. 100 %

Approx. 100 %

E2 line open

2002 ECHO (RM884U)

Author:

Date:

207

DI-38 DIAGNOSTICS

-

ENGINE

WIRING DIAGRAM T2 Throttle Position Sensor

ECM

5V

R-W

1 E6

VC

3

Y-R

11 E6

VTA

2

BR

9 E6

E2

1

E1

A00311

INSPECTION PROCEDURE HINT: 



If DTC P0110 (Intake Air Temp. Circuit Malfunction), P0115 (Engine Coolant Temp. Circuit Malfunction), P0120 (Throttle/Pedal Position Sensor/Switch ”A” Circuit Malfunction) are output simultaneously, E2 (sensor ground) may be open. Read freeze frame data using TOYOTA 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 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.

2002 ECHO (RM884U)

Author:

Date:

208

DI-39 DIAGNOSTICS

1

-

ENGINE

Connect the OBD II scan tool or TOYOTA hand-held tester, read the throttle valve opening percentage. PREPARATION: (a) Connect the OBD II scan tool or TOYOTA hand-held tester to DLC3. (b) Turn the ignition switch ON and push the OBD II scan tool or TOYOTA hand-held tester main switch ON. CHECK: Read the throttle valve opening percentage. OK: FI7052

OK

Throttle valve

Throttle valve opening position expressed as percentage

Fully open

Approx. 70 %

Fully closed

Approx. 10 %

Check for intermittent problems (See page DI-3 ).

NG

2

Check voltage between terminal VC of throttle position sensor connector and body ground.

ON

BE6653 A01842

2 (+)

PREPARATION: (a) Disconnect the throttle position sensor connector. (b) Turn the ignition switch ON. CHECK: Measure voltage between terminal 2 of the throttle position connector and body ground. OK: Voltage: 4.5 - 5.5 V

A02264

NG

Go to step 5.

OK

2002 ECHO (RM884U)

Author:

Date:

209

DI-40 DIAGNOSTICS

3

-

ENGINE

Check throttle position sensor (See page SF-32 ).

Throttle Position Sensor 3 2 1

PREPARATION: Disconnect the throttle position sensor connector. CHECK: Measure resistance between terminals 1, 3 and 2 of the throttle position sensor. OK: Terminals

Throttle valve

Resistance kΩ

1-2



2.5 - 5.9

Fully closed

0.2 - 5.7

Fully open

2.0 - 10.2

A01843

1-3

NG

Replace throttle position sensor.

OK

4

Check voltage between terminals VTA and E2 of ECM connector. ON

VTA

E2 (+)

PREPARATION: (a) Remove the connector cover from the ECM. (b) Turn the ignition switch ON. CHECK: Measure voltage between terminals VTA and E2 of the ECM connector. OK:

(-) A09036

NG

Throttle valve

Voltage

Fully closed

0.3 - 1.0 V

Fully open

3.2 - 4.9 V

Check for open and short in harness and connector between ECM and throttle position sensor (VTA or E2 line) (See page IN-29 ).

OK

Check and replace ECM (See page IN-29 ).

2002 ECHO (RM884U)

Author:

Date:

210

DI-41 DIAGNOSTICS

5

ENGINE

Check voltage between terminals VC and E2 of ECM connector. PREPARATION: (a) Remove the connector cover from the ECM. (b) Turn ignition switch ON. CHECK: Measure voltage between terminals VC and E2 of the ECM connector. OK: Voltage: 4.5 - 5.5 V

ON VC

BE6653 P23813

-

(+)

(-)

E2 A00252

NG

Check and replace ECM (See page IN-29 ).

OK

Check for open in harness and connector between ECM and sensor (VC line) (See page IN-29 ).

2002 ECHO (RM884U)

Author:

Date:

211