SFI SYSTEM (w/ Secondary Air Injection System), Diagnostic DTC:P0120, P0122, P0123, P0220, P0222, P0223, P2135

DTC Code	DTC Name
P0120	Throttle / Pedal Position Sensor / Switch "A" Circuit
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

These DTCs relate to the Throttle Position (TP) sensor.

The Throttle Position (TP) 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 TP sensor has two sensor circuits which transmit a signal respectively, 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 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 Conditions	Trouble Areas
P0120	Output voltage of VTA1 quickly fluctuates beyond lower and upper malfunction thresholds for 2 seconds (1 trip detection logic)	Throttle Position (TP) sensor (built into throttle body) ECM
P0122	Output voltage of VTA1 0.2 V or less for 2 seconds (1 trip detection logic)	Throttle Position (TP) sensor (built into throttle body) Short in VTA1 circuit Open in VC circuit ECM
P0123	Output voltage of VTA1 4.535 V or more for 2 seconds (1 trip detection logic)	Throttle Position (TP) sensor (built into throttle body) Open in VTA1 circuit Open in E2 circuit Short between VC and VTA1 circuits ECM
P0220	Output voltage of VTA2 quickly fluctuates beyond lower and upper malfunction thresholds for 2 seconds (1 trip detection logic)	Throttle Position (TP) 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 (TP) 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 VTA1 between 0.2 V and 2.02 V, for 2 seconds (1 trip detection logic)	Throttle Position (TP) 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): Difference between output voltages of VTA1 and VTA2 0.02 V or less for 0.5 seconds or more Output voltage of VTA1 0.2 V or less, and VTA2 1.75 V or less, for 0.4 seconds or more.	Short between VTA1 and VTA2 circuits Throttle position (TP) sensor (built into throttle body) ECM

Tech Tips

When any of these DTCs are set, check the throttle valve opening angle by entering the following menus: Powertrain / Engine and ECT / Data List / Throttle Position No. 1 and Throttle Position No. 2.

Throttle Position No. 1 denotes the VTA1 signal, and Throttle Position No. 2 denotes the VTA2 signal.

Reference (Normal Condition)

Tester Display	Accelerator Pedal Fully Released	Accelerator Pedal Fully Depressed
Throttle Position No. 1	0.5 to 1.1 V	3.2 to 4.8 V
Throttle Position No. 2	2.1 to 3.1 V	4.6 to 5.0 V

MONITOR DESCRIPTION

The ECM uses the Throttle Position (TP) sensor to monitor the throttle valve opening angle. There are several checks that the ECM performs to confirm the proper operation of the TP 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, and sets 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, and sets 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, and sets a DTC.

If the malfunction is not repaired successfully, a DTC is set 10 seconds after the engine is next started.

FAIL-SAFE

When any of these DTCs as well as other DTCs relating to ETCS (Electronic Throttle Control System) malfunctions are stored, 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 6.5° 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 ignition switch is then turned off.

WIRING DIAGRAM

INSPECTION PROCEDURE

Tech Tips

If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
Read freeze frame data using an intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

PROCEDURE

READ VALUE USING INTELLIGENT TESTER (THROTTLE POSITION SENSOR)

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the tester on.
Enter the following menus: Powertrain / Engine and ECT / Data List / Throttle Position No. 1 and Throttle Position No. 2.

Read the values displayed on the tester.

Result
When Accelerator Pedal Released		When Accelerator Pedal Depressed		Trouble Area	Proceed to
Throttle Position No. 1	Throttle Position No. 2	Throttle Position No. 1	Throttle Position No. 2	Trouble Area	Proceed to
0 to 0.2 V	0 to 0.2 V	0 to 0.2 V	0 to 0.2 V	VC circuit open	A
4.5 to 5.0 V	4.5 to 5.0 V	4.5 to 5.0 V	4.5 to 5.0 V	E2 circuit open
0 to 0.2 V, or 4.5 to 5.0 V	2.1 to 3.1 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	2.1 to 3.1 V (Fail-safe)	VTA1 circuit open or ground short
0.6 to 1.4 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	0.6 to 1.4 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	VTA2 circuit open or ground short
0.5 to 1.1 V	2.1 to 3.1 V	3.2 to 4.8 V (Not fail-safe)	4.6 to 5.0 V (Not fail-safe)	TP sensor circuit normal	B

Tech Tips

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)".

CHECK WHETHER DTC OUTPUT RECURS (THROTTLE POSITION SENSOR DTCS) Click here

CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)

Disconnect the D29 throttle body connector.
Disconnect the D1 ECM connector.

Measure the resistance.

Resistance (Check for open)

Tester Connections	Specified Conditions
VC (D29-5) - VC (D1-18)	Below 1 Ω
VTA (D29-6) - VTA1 (D1-20)	Below 1 Ω
VTA2 (D29-4) - VTA2 (D1-19)	Below 1 Ω
E2 (D29-3) - E2 (D1-28)	Below 1 Ω

Resistance (Check for short)

Tester Connections	Specified Conditions
VC (D29-5) or VC (D1-18) - Body ground	10 kΩ or higher
VTA (D29-6) or VTA1 (D1-20) - Body ground	10 kΩ or higher
VTA2 (D29-4) or VTA2 (D1-19) - Body ground	10 kΩ or higher

Reconnect the throttle body connector.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

INSPECT ECM (VC VOLTAGE)

Disconnect the D29 throttle body connector.
Turn the ignition switch to ON.

Measure the voltage between the terminals of the ECM connector.

Voltage

Tester Connections	Specified Conditions
VC (D1-18) - E2 (D1-28)	4.5 to 5.5 V

Reconnect the throttle body connector.

REPLACE ECM

REPLACE THROTTLE W/MOTOR BODY ASSEMBLY

NEXT

CHECK WHETHER DTC OUTPUT RECURS (THROTTLE POSITION SENSOR DTCS)

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON and turn the tester ON.
Clear DTCs Click here.
Start the engine.
Allow the engine to idle for 15 seconds or more.

Read DTCs.

Result

Display (DTC Output)	Proceed To
P0120, P0121, P0122, P0123, P0220, P0222, P0223 and/or P2135	A
No output	B

END

REPLACE ECM