P0120
2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0120-P0123,P0220,P0222,P0223,P2135: Throttle / Pedal Position Sensor / Switch "A" Circuit Malfunction
DESCRIPTION
HINT
- These DTCs relate to the throttle position sensor.
The throttle position sensor is mounted on the throttle body, and detects the opening angle of the throttle valve. This sensor is a non-contact type sensor. It uses hall-effect elements in order to yield accurate signals even in extreme driving conditions, such as at high speeds as well as very low speeds.
The throttle position sensor has 2 sensor circuits, each of which transmits a signal, VTA1 and VTA2. VTA1 is used to detect the throttle valve angle and VTA2 is used to detect malfunctions in VTA1. The sensor signal voltages vary between 0 V and 5 V in proportion to the throttle valve opening angle, and are transmitted to the VTA1 terminals of the ECM.
As the valve closes, the sensor output voltage decreases and as the valve opens, the sensor output voltage increases. The ECM calculates the throttle valve opening angle according to these signals and controls the throttle actuator in response to driver inputs. These signals are also used in calculations such as air fuel ratio correction, power increase correction and fuel-cut control.
HINT
- When any of these DTCs are output, check the throttle valve opening angle using the Techstream. Enter the following menus: Powertrain / Engine / Data List / All Data / Throttle Position No. 1 and Throttle Position No. 2.
- Throttle Position No. 1 is the VTA1 signal, and Throttle Position No. 2 is the VTA2 signal.
Reference (Normal Condition):
MONITOR DESCRIPTION
P0120, P0122, P0123, P0220, P0222, P0223, P2135
The ECM uses the throttle position sensor to monitor the throttle valve opening angle. There are several checks that the ECM performs to confirm the proper operation of the throttle position sensor.
- A specific voltage difference is expected between the sensor terminals, VTA1 and VTA2, for each throttle valve opening angle. If the difference between VTA1 and VTA2 is incorrect, the ECM interprets this as a malfunction in the sensor circuit, and stores a DTC.
- VTA1 and VTA2 each have a specific voltage range. If VTA1 or VTA2 is outside the normal operating range, the ECM interprets this as a malfunction in the sensor circuit, and stores a DTC.
- VTA1 and VTA2 should never be close to the same voltage level. If VTA1 is within 0.02 V of VTA2, the ECM determines that there is a short circuit in the sensor circuit, and stores a DTC.
If the malfunction is not repaired successfully, a DTC is stored 10 seconds after the engine is next started.
P0121
This sensor transmits 2 signals: VTA1 and VTA2. VTA1 is used to detect the throttle opening angle and VTA2 is used to detect malfunctions in VTA1. The ECM performs several checks to confirm the proper operation of the throttle position sensor and VTA1.
For each throttle opening angle, a specific voltage difference is expected between the outputs of VTA1 and VTA2. If the output voltage difference between the 2 signals deviates from the normal operating range, the ECM interprets this as a malfunction in the throttle position sensor. The ECM illuminates the MIL and stores the DTC.
If the malfunction is not repaired successfully, the DTC is stored 2 seconds after the engine is next started.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
P0120, P0122, P0123, P0220, P0222, P0223, P02135
P0121
TYPICAL MALFUNCTION THRESHOLDS
P0120
P0121
P0122
P0123
P0220
P0222
P0223
P2135 Case 1
P2135 Case 2
COMPONENT OPERATING RANGE
CONFIRMATION DRIVING PATTERN
1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG) and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Reading and Clearing Diagnostic Trouble Codes.
4. Turn the engine switch off and wait for 30 seconds.
5. Turn the engine switch on (IG) and turn the Techstream on [A].
6. Start the engine.
7. With the vehicle stationary, fully depress and release the accelerator pedal [B].
8. Idle the engine for 2 seconds or more [C].
9. Enter the following menus: Powertrain / Engine / Trouble Codes.
10. Read the DTC [D].
11. If a DTC is output, the system is malfunctioning.
HINT
If a DTC is not output, perform the following procedure.
12. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
13. Input the DTC: P0120, P0121, P0122, P0123, P0220, P0222, P0223 or P2135.
14. Check the DTC judgment result.
HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [B] and [C] again.
15. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
16. Check the judgment result.
HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.
17. If the test result is INCOMPLETE or UNKNOWN and no DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.
HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
FAIL-SAFE
When any of these DTCs, as well as other DTCs relating to electronic throttle control system malfunctions are set, the ECM enters fail-safe mode. During fail-safe mode, the ECM cuts the current to the throttle actuator, and the throttle valve is returned to a 6° throttle angle by the return spring. The ECM then adjusts the engine output by controlling the fuel injection (intermittent fuel-cut) and ignition timing, in accordance with the accelerator pedal opening angle, to allow the vehicle to continue at a minimal speed. If the accelerator pedal is depressed firmly and gently, the vehicle can be driven slowly.
Fail-safe mode continues until a pass condition is detected, and the engine switch is then turned off.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT
Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
1. READ VALUE USING TECHSTREAM (THROTTLE POSITION SENSOR)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Data List / All Data / Throttle Position No. 1 and Throttle Position No. 2.
(e) Read the values displayed on the Techstream.
Result
HINT
- DTC P0121 is stored when the voltages output from VTA1 and VTA2 are not consistent with the characteristics of the sensors. Therefore, check the Freeze Frame Data when this DTC is output. Use the following formula to confirm relative fluctuations in voltage.
Features of sensor output:
VTA2 x 0.8 is approximately equal to VTA1 + 1.11 V
VTA1: Throttle Position No. 1
VTA2: Throttle position No. 2
- If DTC P0121 is output, proceed to the "CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)".
B -- CHECK WHETHER DTC OUTPUT RECURS (THROTTLE POSITION SENSOR DTCs)
A -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)
(a) Disconnect the throttle body connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):
Standard resistance (Check for short):
(d) Reconnect the ECM connector.
(e) Reconnect the throttle body connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (THROTTLE POSITION SENSOR - ECM)
OK -- Continue to next step.
3. INSPECT ECM (VC VOLTAGE)
(a) Disconnect the throttle body connector.
(b) Turn the engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:
(d) Reconnect the throttle body connector.
NG -- REPLACE ECM Removal
OK -- Continue to next step.
4. REPLACE THROTTLE BODY ASSEMBLY
(a) Replace the throttle body Removal.
NEXT -- Continue to next step.
5. CHECK WHETHER DTC OUTPUT RECURS (THROTTLE POSITION SENSOR DTCs)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(e) Start the engine.
(f) Allow the engine to idle for 15 seconds or more.
(g) Enter the following menus: Powertrain / Engine / Trouble Codes.
(h) Read the DTCs.
Result:
B -- END
A -- REPLACE ECM Removal