ECD SYSTEM, Diagnostic DTC:P0122, P0123

DTC Code	DTC Name
P0122	Throttle / Pedal Position Sensor / Switch "A" Circuit Low Input
P0123	Throttle / Pedal Position Sensor / Switch "A" Circuit High Input

DESCRIPTION

The throttle position sensor is built into the diesel throttle body and detects the opening angle of the throttle valve. This sensor is an electronic sensor and uses Hall-effect elements.

When the throttle valve is fully closed, a voltage of approximately 0.7 V is applied to terminal VTA1 of the ECM. The voltage applied to terminal VTA1 of the ECM increases in proportion to the opening angle of the throttle valve and becomes approximately 3.9 to 4.2 V when the throttle valve is fully opened.

The ECM determines the vehicle driving conditions from the signals input to its VTA1 terminal. The data is one of the inputs used for EGR control, etc.


*1	Throttle Position Sensor
*2	Magnet
*3	Hall IC

P0122
DTC Detection Drive Pattern	DTC Detection Condition	Trouble Area
Ignition switch is ON	Throttle position sensor output (VTA1) is less than 0.2 V for 3 seconds. (1 trip detection logic)	Throttle position sensor Open or short in VTA1 circuit Open in VC circuit ECM

P0123
DTC Detection Drive Pattern	DTC Detection Condition	Trouble Area
Ignition switch is ON	Throttle position sensor output (VTA1) is more than 4.8 V for 3 seconds. (1 trip detection logic)	Throttle position sensor Open in E2 circuit VC and VTA1 circuits are short-circuited ECM

Related Data List
DTC No.	Data List
P0122	Target Throttle Position Actual Throttle Position Throttle Sensor Volt %
P0123

Tech Tips

Throttle position sensor output voltage "Throttle Sensor Volt %" is converted using 5 V = 100 %.
If DTC P0122 or P0123 is stored, the following symptoms may appear:

Intake booming noise
Black smoke
Lack of power
Vibration at engine stop
Turbo overspeed, turbo damage

MONITOR DESCRIPTION

When the output voltage of the throttle position sensor deviates from the normal operating range (between 0.2 V and 4.8 V) for more than 3 seconds, the ECM interprets this as a malfunction of the sensor circuit and illuminates the MIL.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

Note

When replacing the ECM, the ECM needs Registration and Initialization Click here.

Tech Tips

When the ECM must be replaced, before replacing the ECM, perform the "Learning Values Save" function using the intelligent tester. Then after installing the new ECM, perform all of the initialization/registrations for the "Learning Values Write" function by following the instructions shown on the tester display.
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, and other data from the time the malfunction occurred.

PROCEDURE

CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)

Disconnect the diesel throttle body assembly 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
B81-5 (VC) - A59-46 (VCTA)	Always	Below 1 Ω
B81-6 (VTA) - A59-45 (VTA1)	Always	Below 1 Ω
B81-3 (E2) - A59-47 (ETA)	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
B81-5 (VC) or A59-46 (VCTA) - Body ground	Always	10 kΩ or higher
B81-6 (VTA) or A59-45 (VTA1) - Body ground	Always	10 kΩ or higher
B81-3 (E2) or A59-47 (ETA) - Body ground	Always	10 kΩ or higher

Reconnect the diesel throttle body assembly connector.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR Click here

INSPECT ECM (VC VOLTAGE)

Text in Illustration

*a
Front view of wire harness connector

(to Diesel Throttle Body Assembly)

Disconnect the diesel throttle body assembly connector.
Turn the ignition switch to ON.

Text in Illustration
*a	Front view of wire harness connector (to Diesel Throttle Body Assembly)

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

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
B81-5 (VC) - B81-3 (E2)	Ignition switch ON	4.5 to 5.5 V

Reconnect the diesel throttle body assembly connector.

REPLACE ECM Click here

REPLACE DIESEL THROTTLE BODY ASSEMBLY
1. Replace diesel throttle body assembly Click here.
2. Turn the ignition switch to ON.
3. Turn the ignition switch off and wait for 30 seconds or more.
NEXT

READ VALUE USING INTELLIGENT TESTER (ACTUAL THROTTLE POSITION)

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON and turn the tester on.
Clear the DTCs Click here.
Turn the ignition switch off and wait for 30 seconds or more.
Start the engine and wait for 30 seconds or more.
Enter the following menus: Powertrain / Engine and ECT / Data List / Actual Throttle position.

Check the movement of the throttle valve when the ignition switch is turned off from the engine idling.

Tech Tips

When reading the values of Data List, confirm that PM regeneration is not activating (value of "After Injection Period" is 0) by entering the following menus: Powertrain / Engine and ECT / Data List / After Injection Period.

If PM regeneration is activating (value of "After Injection Period" is not 0), drive the vehicle until the PM regeneration is complete (value of "After Injection Period" becomes 0).

Standard

Condition	Tester Display
Idling	0 to 90%
Ignition switch off from engine idling	Move to 100% once, then return to 0%

END

REPLACE ECM
1. Replace the ECM Click here.
NEXT
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here
REPAIR OR REPLACE HARNESS OR CONNECTOR

NEXT
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED
1. Connect the intelligent tester to the DLC3.
2. Clear the DTCs Click here.
3. Turn the ignition switch off and wait for 30 seconds or more.
4. Start the engine and wait for 30 seconds or more.
5. Enter the following menus: Powertrain / Engine and ECT / DTC.
6. Confirm that the DTC is not output again.
NEXT
END