P0120
NOTE: If DTC P0120 (0403) is displayed with DTC P0510 (0203), first perform the trouble diagnosis for "DTC P0510 CLOSED THROTTLE POSITION SWITCH".
COMPONENT DESCRIPTION
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 Reference Value in Data Monitor Mode
Specification data are reference values.
ECM Terminals and Reference Value
Specification data are reference values and are measured between each terminal and 32 (ECM ground).
On Board Diagnosis Logic
DTC Confirmation Procedure
NOTE:
- 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".
- If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 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 10V at idle.
- This test may be conducted with the drive wheels lifted in the shop or by driving the vehicle. If a road test is expected to be easier, it is unnecessary to lift the vehicle.
With CONSULT
1. Turn ignition switch "ON" and select "DATA MONITOR" mode with CONSULT.
2. Start engine and maintain the following conditions for at least 5 consecutive seconds.
Vehicle speed More than 4 kph (2 MPH)
Selector level Suitable position except "P" or "N" position
3. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
With GST
1. Start engine and maintain the following conditions for at least 5 consecutive seconds.
Vehicle speed More than 4 kph (2 MPH)
Selector level Suitable position except "P" or "N" position
2. Select "MODE 7" with GST.
3. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
Without Scan Tool
1. Start engine and maintain the following conditions for at least 5 consecutive seconds.
Vehicle speed More than 4 kph (2 MPH)
Selector level Suitable position except "P" or "N" position
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Turn ignition switch "ON" and perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.
4. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
PROCEDURE FOR MALFUNCTION B
With CONSULT
1. Turn ignition switch "ON".
2. Select "DATA MONITOR" mode with CONSULT.
3. Start engine and let it idle for at least 10 seconds.
Selector level Suitable position except "P" or "N"
Brake pedal Depressed
Vehicle speed 0 kph (0 MPH)
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
1. 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
Selector level Suitable position except "P" or "N"
Brake pedal Depressed
Vehicle speed 0 kph (0 MPH)
2. Select "MODE 7" with GST
3. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
Without Scan Tool
1. 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
Selector level Suitable position except "P" or "N"
Brake pedal Depressed
Vehicle speed 0 kph (0 MPH)
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Turn ignition switch "ON" and perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.
4. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
PROCEDURE FOR MALFUNCTION C
CAUTION: Always drive vehicle at a safe speed.
With CONSULT
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Turn ignition switch "ON".
4. Select "MANU TRIG" and "HI SPEED" in "DATA MONITOR" mode with CONSULT.
5. Select "THRTL POS SEN" and "ABSOL TH.P/S" in "DATA MONITOR" mode with CONSULT.
6. Press RECORD on CONSULT 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 4V.
If NG, go to "Diagnostic Procedure" below. If OK, go to following step.
8. Select "AUTO TRIG" in "DATA MONITOR" mode with CONSULT.
9. Maintain the following conditions for at least 10 consecutive seconds.
CMPS.RPM (REF) More than 2,000 rpm
MAS AIR/FL SE More than 3V
COOLAN TEMP/S More than 70°C (158°F)
IACV-AAC/V Less than 80%
Selector lever Suitable position
Driving location Driving vehicle uphill (Increased engine load) will help maintain the driving conditions required for this test.
10. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
With GST
1. Start engine and warm it up to normal operating temperature.
2. Maintain the following conditions for at least 10 consecutive seconds.
Gear position: Suitable position
Engine speed: More than 2,000 rpm
Engine coolant temperature: More than 70 °C (159 °F)
Voltage between ECM terminal 54 (Mass air flow sensor signal) and ground: More than 3V
3. Select "MODE 7" with GST.
4. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
Without Scan Tool
1. Start engine and warm it up to normal operating temperature.
2. Maintain the following conditions for at least 10 consecutive seconds.
Gear position: Suitable position
Engine speed: More than 2,000 rpm
Voltage between ECM terminal 54 (Mass air flow sensor signal) and ground: More than 3V
Voltage between ECM terminal 59 (Engine coolant temperature sensor signal) and ground: Less than 1.5V
3. Stop the vehicle, turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
4. Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.
5. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
EC-TPS-01:
EC-TPS-01 Connectors View:
Wiring Diagram
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Component Inspection
With CONSULT
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.
8. Check voltage of "THRTL POS SEN".
Voltage measurement must be made with throttle position sensor installed in vehicle.
Throttle valve conditions THRTL POS SEN
Completely closed (a) 0.15- 0.85V
Partially open Between (a) and (b)
Completely open (b) 3.5 - 4.7V
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 Tools
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 (-300mmHg, 11.81inHg)] until the throttle drum becomes free from the rod of the throttle opener.
6. Turn ignition switch ON.
7. Check voltage between ECM terminal 23 (Throttle position sensor signal) and ground.
Voltage measurement must be made with throttle position sensor installed in vehicle.
Throttle valve conditions Voltage
Completely closed (a) 0.15 - 0.85V
Partially open Between (a) and (b)
Completely open (b) 3.5 - 4.7 V
If NG, adjust closed 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.