2Az-Fe Engine Control. Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit

The accelerator pedal position sensor is mounted on the accelerator pedal bracket and has 2 sensor circuits: VPA (main) and VPA2 (sub). This sensor is a non-contact type and uses Hall-effect elements in order to yield accurate signals even in extreme conditions. The voltage from this sensor, which is applied to terminals VPA and VPA2 of the ECM, varies between 0.5 V and 4.75 V in proportion to the operating angle of the accelerator pedal (throttle valve). A signal from VPA indicates the actual accelerator pedal opening angle (throttle valve opening angle) and is used for engine control. A signal from VPA2 conveys the status of the VPA circuit and is used to check the APP sensor itself.
The ECM monitors the actual accelerator pedal opening angle (throttle valve opening angle) through the signals from VPA and VPA2, and controls the throttle actuator according to these signals.

Corolla. Zre142 Aze141.2Az-Fe Engine Control.Sfi System.
Dtc
P2120 Throttle / Pedal Position Sensor / Switch D Circuit

DTC No.	DTC Detection Condition	Trouble Area
P2120	VPA fluctuates rapidly beyond upper and lower malfunction thresholds for 0.5 seconds or more (1 trip detection logic)	Accelerator pedal position sensor ECM
P2122	VPA 0.4 V or less for 0.5 seconds or more when accelerator pedal depressed (1 trip detection logic)	Accelerator pedal position sensor Open in VCPA circuit Open or ground short in VPA circuit ECM
P2123	VPA 4.8 V or more for 2.0 seconds or more (1 trip detection logic)	Accelerator pedal position sensor Open in EPA circuit ECM
P2125	VPA2 fluctuates rapidly beyond upper and lower malfunction thresholds for 0.5 seconds or more (1 trip detection logic)	Accelerator pedal position sensor ECM
P2127	VPA2 1.2 V or less for 0.5 seconds or more when accelerator pedal depressed (1 trip detection logic)	Accelerator pedal position sensor Open in VCP2 circuit Open or ground short in VPA2 circuit ECM
P2128	Conditions (a) and (b) continue for 2.0 seconds or more (1 trip detection logic): (a) VPA2 4.8 V or more (b) VPA between 0.4 V and 3.45 V	Accelerator pedal position sensor Open in EPA2 circuit ECM
P2138	Condition (a) or (b) continues for 2.0 seconds or more (1 trip detection logic): (a) Difference between VPA and VPA2 0.02 V or less (b) VPA 0.4 V or less, and VPA2 1.2 V or less	Short between VPA and VPA2 circuits Accelerator pedal position sensor ECM

HINT:

When any of these DTCs are set, check the accelerator pedal position sensor voltage by entering the following menus: Powertrain / Engine and ECT / Data List / Gas Throttle / Accel Sensor Out No. 1 and Accel Sensor Out No. 2.

Trouble Area	Accel Sensor Out No. 1 When Accelerator Pedal Fully Released	Accel Sensor Out No. 2 When Accelerator Pedal Fully Released	Accel Sensor Out No. 1 When Accelerator Pedal Fully Depressed	Accel Sensor Out No. 2 When Accelerator Pedal Fully Depressed
VCP circuit open	0 to 0.2 V	0 to 0.2 V	0 to 0.2 V	0 to 0.2 V
Open or ground short in VPA circuit	0 to 0.2 V	1.2 to 2.0 V	0 to 0.2 V	3.4 to 4.75 V
Open or ground short in VPA2 circuit	0.5 to 1.1 V	0 to 0.2 V	2.6 to 4.5 V	0 to 0.2 V
EPA circuit open	4.5 to 4.98 V	4.5 to 4.98 V	4.5 to 4.98 V	4.5 to 4.98 V
Normal condition	0.5 to 1.1 V	1.2 to 2.0 V	2.6 to 4.5 V	3.4 to 4.75 V

HINT:

Accelerator pedal positions are expressed as voltages.

MONITOR DESCRIPTION

When either output voltage of VPA or VPA2 deviates from the standard range, or the difference between the output voltages of the 2 sensor circuits is more than the threshold, the ECM determines that there is a malfunction in the accelerator pedal position sensor. The ECM then illuminates the MIL and stores a DTC.
Example:
When the output voltage of VPA is less than 0.4 V for more than 0.5 seconds when the accelerator pedal is fully depressed, DTC P2122 is stored.

MONITOR STRATEGY

Related DTCs	P2120: Accelerator pedal position sensor 1 range check (chattering) P2122: Accelerator pedal position sensor 1 range check (low voltage) P2123: Accelerator pedal position sensor 1 range check (high voltage) P2125: Accelerator pedal position sensor 2 range check (chattering) P2127: Accelerator pedal position sensor 2 range check (low voltage) P2128: Accelerator pedal position sensor 2 range check (high voltage) P2138: Accelerator pedal position sensor range check (correlation)
Required Sensors/Components (Main)	Accelerator pedal position sensor
Required Sensors/Components (Related)	-
Frequency of Operation	Continuous
Duration	0.5 seconds: P2120, P2122, P2125 and P2127 2.0 seconds: P2123, P2128 and P2138
MIL Operation	Immediate
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs are not present	None
Either of following conditions 1 or 2 is met:	-
1. Ignition switch	0.012 seconds or more
2. Electronic Throttle actuator power	On

TYPICAL MALFUNCTION THRESHOLDS

P2120
Either of following conditions 1 or 2 is met:	-
1. VPA voltage when VPA2 voltage 0.04 V or more	0.4 V or less
2. VPA voltage	4.8 V or more

P2122
VPA voltage when VPA2 voltage 0.04 V or more	0.4 V or less

P2123
VPA voltage	4.8 V or more

P2125
Either of following conditions 1 or 2 met:	-
1. VPA2 voltage when VPA voltage 0.04 V or more	1.2 V or less
2. VPA2 voltage when VPA voltage 0.4 to 3.45 V	4.8 V or more

P2127
VPA2 voltage when VPA voltage 0.04 V or more	1.2 V or less

P2128
VPA2 voltage when VPA voltage 0.4 to 3.45 V	4.8 V or more

P2138
Either of following conditions A or B met:	-
Condition A	-
Difference between VPA and VPA 2 voltages	0.02 V or less
Condition B	-
VPA voltage	0.4 V or less
VPA2 voltage	1.2 V or less

COMPONENT OPERATING RANGE

VPA voltage	0.4 to 4.8 V
VPA2 voltage	1.2 to 4.8 V
Difference between VPA and VPA2 voltages	More than 0.02 V

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the ignition switch to ON and turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the Techstream on [A].
Fully depress and release the accelerator pedal [B].
Check that 5 seconds or more have elapsed since the ignition switch is turned ON.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].
Read the pending DTCs.
HINT:
1. If a pending DTC is output, the system is malfunctioning.
2. If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P2120, P2122, P2123, P2125, P2127, P2128 or P2138.

Check the DTC judgment result.

Techstream Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform steps [B] and [C] again.

If no pending DTC is output, perform a universal trip and check for permanent DTCs (COROLLA_ZRE142 RM000000PDK0ZBX.html).
HINT:
1. If a permanent DTC is output, the system is malfunctioning.
2. If no permanent DTC is output, the system is normal.

FAIL-SAFE

When DTC P2120, P2121, P2122, P2123, P2125, P2127, P2128 or P2138 is stored, the ECM enters fail-safe mode. If either of the 2 sensor circuits malfunctions, the ECM uses the remaining circuit to calculate the accelerator pedal position to allow the vehicle to continue driving. If both of the circuits malfunction, the ECM regards the accelerator pedal as being released. As a result, the throttle valve is closed and the engine idles.
Fail-safe mode continues until a pass condition is detected, and the ignition switch is 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 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.

1.READ VALUE USING TECHSTREAM (ACCELERATOR POSITION SENSOR)

Connect the Techstream to the DLC3.

Turn the ignition switch to ON.

Turn the Techstream on.

Enter the following menus: Powertrain / Engine and ECT / Data List / Gas Throttle / Accel Sensor Out No. 1 and Accel Sensor Out No. 2.

Read the value displayed on the Techstream.

Standard Voltage:

Accelerator Pedal Operation	Accel Sensor Out No. 1	Accel Sensor Out No. 2	Difference between Accel Sensor Out No. 1 and Accel Sensor Out No. 2
Fully Released	0.5 to 1.1 V	1.2 to 2.0 V	More than 0.02 V
Fully Depressed	2.6 to 4.5 V	3.4 to 4.75 V	More than 0.02 V

Go to step 2

CHECK FOR INTERMITTENT PROBLEMS (COROLLA_ZRE142 RM000000PDQ0VNX.html)

2.CHECK HARNESS AND CONNECTOR (ACCELERATOR PEDAL POSITION SENSOR - ECM)

Disconnect the accelerator pedal position sensor 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
A3-6 (VPA) - A50-55 (VPA)	Always	Below 1 Ω
A3-5 (EPA) - A50-59 (EPA)	Always	Below 1 Ω
A3-4 (VCPA) - A50-57 (VCPA)	Always	Below 1 Ω
A3-3 (VPA2) - A50-56 (VPA2)	Always	Below 1 Ω
A3-2 (EPA2) - A50-60 (EPA2)	Always	Below 1 Ω
A3-1 (VCP2) - A50-58 (VCP2)	Always	Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection	Condition	Specified Condition
A3-6 (VPA) or A50-55 (VPA) - Body ground	Always	10 kΩ or higher
A3-4 (VCPA) or A50-57 (VCPA) - Body ground	Always	10 kΩ or higher
A3-3 (VPA2) or A50-56 (VPA2) - Body ground	Always	10 kΩ or higher
A3-1 (VCP2) or A50-58 (VCP2) - Body ground	Always	10 kΩ or higher

Reconnect the accelerator pedal position sensor connector.

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (ACCELERATOR PEDAL POSITION SENSOR - ECM)

OK

3.CHECK ECM (VCPA AND VCP2 VOLTAGE)

Disconnect the accelerator pedal position sensor connector.

Turn the ignition switch to ON.

Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection
Condition
Specified Condition
A3-4 (VCPA) - A3-5 (EPA)
Ignition switch ON
4.5 to 5.5 V
A3-1 (VCP2) - A3-2 (EPA2)
Ignition switch ON
4.5 to 5.5 V

Reconnect the accelerator pedal position sensor connector.

REPLACE ECM (COROLLA_ZRE142 RM000002WT402ZX.html)

OK

4.REPLACE ACCELERATOR PEDAL ASSEMBLY

Replace the accelerator pedal assembly (COROLLA_ZRE142 RM000003D3500AX.html).

NEXT

5.CHECK WHETHER DTC OUTPUT RECURS (ACCELERATOR PEDAL POSITION SENSOR DTCS)

Connect the Techstream to the DLC3.

Turn the ignition switch to ON.

Turn the Techstream on.

Clear the DTCs (COROLLA_ZRE142 RM000000PDK0ZBX.html).

Start the engine.

Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

Read DTCs.

Result:

Result
Proceed to
P2120, P2122, P2123, P2125, P2127, P2128, and/or P2138
A
No output
B

END

REPLACE ECM (COROLLA_ZRE142 RM000002WT402ZX.html)

Result	Proceed to
P2120, P2122, P2123, P2125, P2127, P2128, and/or P2138	A
No output	B