SFI SYSTEM, Diagnostic DTC:P0120, P0122, P0123, P0220, P0222, P0223, P2135

DTC Code	DTC Name
P0120	Throttle / Pedal Position Sensor / Switch "A" Circuit Malfunction
P0122	Throttle / Pedal Position Sensor / Switch "A" Circuit Low Input
P0123	Throttle / Pedal Position Sensor / Switch "A" Circuit High Input
P0220	Throttle / Pedal Position Sensor / Switch "B" Circuit
P0222	Throttle / Pedal Position Sensor / Switch "B" Circuit Low Input
P0223	Throttle / Pedal Position Sensor / Switch "B" Circuit High Input
P2135	Throttle / Pedal Position Sensor / Switch "A" / "B" Voltage Correlation

DESCRIPTION

Tech Tips

This electronic throttle control system does not use a throttle cable.

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, and 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 two sensor circuits, each of which transmits a signal, VTA and VTA2. VTA is used to detect the throttle valve angle and VTA2 is used to detect malfunctions in VTA. The sensor signal voltages vary between 0 V and 5 V in proportion to the throttle valve opening angle, and are transmitted to the VTA 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.

DTC No.	DTC Detection Condition	Trouble Area
P0120	Output voltage of VTA quickly fluctuates beyond lower and upper malfunction thresholds for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) ECM
P0122	Output voltage of VTA 0.2 V or less for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) Short in VTA circuit Open in VC circuit ECM
P0123	Output voltage of VTA 4.535 V or more for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) Open in VTA circuit Open in E2 circuit Short between VC and VTA circuits ECM
P0220	Output voltage of VTA2 quickly fluctuates beyond lower and upper malfunction thresholds for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) ECM
P0222	Output voltage of VTA2 1.75 V or less for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) Short in VTA2 circuit Open in VC circuit ECM
P0223	Output voltage of VTA2 4.8 V or more, and VTA between 0.2 V and 2.02 V, for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) Open in VTA2 circuit Open in E2 circuit Short between VC and VTA2 circuits ECM
P2135	Either condition (a) or (b) is met (1 trip detection logic): (a) Difference between output voltages of VTA and VTA2 0.02 V or less for 0.5 seconds or more (b) Output voltage of VTA 0.2 V or less, and VTA2 1.75 V or less, for 0.4 seconds or more	Short between VTA and VTA2 circuits Throttle position sensor (built into throttle body) ECM

MONITOR DESCRIPTION

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, VTA and VTA2, for each throttle valve opening angle. If the difference between VTA and VTA2 is incorrect, the ECM interprets this as a malfunction in the sensor, and sets a DTC.
VTA and VTA2 each have a specific voltage range. If VTA or VTA2 is outside the normal operating range, the ECM interprets this as a malfunction in the sensor, and sets a DTC.
VTA and VTA2 should never be close to the same voltage level. If VTA is within 0.02 V of VTA2, the ECM determines that there is a short circuit in the sensor, and sets a DTC.

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 off, and the throttle valve is returned to a 7° 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.

WIRING DIAGRAM

INSPECTION PROCEDURE

Tech Tips

If other DTCs relating to different systems that have terminal ETA as the ground terminal are output simultaneously, terminal ETA may have an open circuit.
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. 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

CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)

Disconnect the throttle body connector.
Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
E17-5 (VC) - E4-34 (VCTA)	Always	Below 1 Ω
E17-6 (VTA) - E4-26 (VTA)	Always	Below 1 Ω
E17-4 (VTA2) - E4-27 (VTA2)	Always	Below 1 Ω
E17-3 (E2) - E4-35 (ETA)	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
E17-5 (VC) or E4-34 (VCTA)- Body ground	Always	10 kΩ or higher
E17-6 (VTA) or E4-26 (VTA) - Body ground	Always	10 kΩ or higher
E17-4 (VTA2) or E4-27 (VTA2) - Body ground	Always	10 kΩ or higher