P0120

Component Description

NOTE: If DTC P0120 (0403) is displayed with DTC P0510 (0203), first perform trouble diagnosis for DTC P0510.

The throttle position sensor responds to the accelerator pedal movement. This sensor is a kind of potentiometer which transforms the throttle position into output voltage, and emits the voltage signal to the ECM. In addition, the sensor detects the opening and closing speed of the throttle valve and feeds the voltage signal to the ECM.

Idle position of the throttle valve is determined by the ECM receiving the signal from the throttle position sensor. This sensor controls engine operation such as fuel cut. On the other hand, the "Wide open and closed throttle position switch", which is built into the throttle position sensor unit, is not used for engine control.

Consult-II Reference Value In Data Monitor Mode:

On Board Diagnosis Logic:

DTC Confirmation Procedure
Perform "PROCEDURE FOR MALFUNCTION A" first. If the 1st trip DTC cannot be confirmed, perform "PROCEDURE FOR MALFUNCTION B". If there is no problem on "PROCEDURE FOR MALFUNCTION B", perform "PROCEDURE FOR MALFUNCTION C".

NOTE: If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch "OFF" and wait at least 10 seconds before conducting the next test.

PROCEDURE FOR MALFUNCTION A

CAUTION: Always drive vehicle at a safe speed.

TESTING CONDITION:
- Before performing the following procedure, confirm that battery voltage is more than 10 V at idle.
- This test may be conducted in the shop with the drive wheels lifted or by driving the vehicle. If a road test is expected to be easier, it is unnecessary to lift the vehicle.

With CONSULT-II
1. Turn ignition switch "ON" and select "DATA MONITOR" mode with CONSULT-II.

2. Start engine and maintain the following conditions for at least 5 consecutive seconds.
3. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

With GST
Follow the procedure "With CONSULT-II" above.

PROCEDURE FOR MALFUNCTION B

With CONSULT-II
1. Turn ignition switch "ON".
2. Select "DATA MONITOR" mode with CONSULT-II.

3. Start engine and let it idle for at least 10 seconds.

If idle speed is over 1,000 rpm, maintain the following conditions for at least 10 seconds to keep engine speed below 1,000 rpm.

4. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

With GST
Follow the procedure "With CONSULT-II" above.

PROCEDURE FOR MALFUNCTION C

CAUTION: Always drive vehicle at a safe speed.

With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch "OFF" and wait at least 10 seconds.
3. Turn ignition switch "ON".
4. Select "MANU TRIG" in "DATA MONITOR" mode with CONSULT-II.
5. Select "THRTL POS SEN" and "ABSOL TH.P/S" in "DATA MONITOR" mode with CONSULT-II.

6. Press RECORD on CONSULT-II SCREEN at the same time accelerator pedal is depressed.

7. Print out the recorded graph and check the following:
- The voltage rise is linear in response to accelerator pedal depression.
- The voltage when accelerator pedal is fully depressed is approximately 4 V.
If NG, go to "Diagnostic Procedure" below.
If OK, go to following step.

8. Select "AUTO TRIG" in "DATA MONITOR" mode with CONSULT-II.

9. Maintain the following conditions for at least 10 consecutive seconds.
10. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

With GST

1. Maintain the following conditions for at least 10 consecutive seconds.
2. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

EC-TPS-01:

EC-TPS-01 Connector View:

ECM Terminals And Reference Value:

Wiring Diagram

Diagnostic Procedure Steps 1 - 4:

Diagnostic Procedure Steps 5 - 7:

Diagnostic Procedure Steps 8 - 12:

Diagnostic Procedure Steps 13 - 14:

Diagnostic Procedure

Component Inspection

With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Stop engine (ignition switch OFF).

3. Remove the vacuum hose connected to the throttle opener.
4. Connect suitable vacuum hose to the vacuum pump and the opener.
5. Apply vacuum [more than -40.0 kPa (-300 mmHg, -11.81 inHg)] until the throttle drum becomes free from the rod of the throttle opener.
6. Turn ignition switch ON.

7. Select "DATA MONITOR" mode with CONSULT-II.

8. Check voltage of "THRTL POS SEN" under the following conditions.

NOTE: Voltage measurement must be made with throttle position sensor installed in vehicle.

If NG, adjust closed throttle position switch. Refer to "Basic Inspection".

9. If it is impossible to adjust closed throttle position switch in "Basic Inspection", replace throttle position sensor.

Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Stop engine (ignition switch OFF).

7. Check voltage between ECM terminal 92 (Throttle position sensor signal) and ground under the following conditions.

NOTE: Voltage measurement must be made with throttle position sensor installed in vehicle.

If NG, adjust throttle position switch. Refer to "Basic Inspection".

8. If it is impossible to adjust closed throttle position switch in "Basic Inspection", replace throttle position sensor.