Fuel System > Engine Control System > P0123 Throttle/Pedal Position Sensor/Switch \

Component Location

General Description

The Electronic Throttle Control(ETC) system is made of the components throttle body, Throttle Position Sensor(TPS)1&2 and Accelerator Position Sensor(APS) 1&2. TPS1&2 are sharing the same source voltage and ground.The throttle valve opening is control by throttle motor which is controlled by Engine Control Module(PCM).The opposite position indicator shows inverted signal characteristics.TPS1 output voltage increases smoothly in proportion with the throttle valve opening angle after starting. TPS2 output voltage decreases in inverse proportion with the throttle valve opening angle after starting. TPS provides feedback to the PCM to control the throttle motor in order to control the throttle valve opening angle properly in response to the driving condition.

DTC Description

Checking output signals from TPS1 every 8.5 sec. under detecting condition, if an output signal is above 4.75V for more than 0.1 sec., PCM sets P0123. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition

Item

Detecting Condition

Possible Cause

DTC Strategy

•	signal high

•	Poor connection

•	Open or short to battery in signal harness

•	Open in ground harness

•

TPS

•

PCM

Enable condition

•

IG "ON

threshold value

•	The voltage of TPS >4.75V

diagnosis time

•	Continuous (more than 0.1 sec. failure for every 8.5 sec.test)

MIL ON condition

•	2 driving cycles

Specification

Throttle opening ( ° )	Output voltage(V) [Vref=5.0]
Throttle opening ( ° )	TPS1	TPS2
0°	0.0V	5.0V
10°	0.5V	4.5V
20°	0.9V	4.1V
30°	1.4V	3.6V
40°	1.8V	3.2V
50°	2.3V	2.7V
60°	2.7V	2.3V
70°	3.2V	1.8V
80°	3.6V	1.4V
90°	4.1V	0.9V
100°	4.5V	0.5V
110°	5.0V	0.0V

Schematic Diagram

Signal Waveform And Data

Monitor DTC Status

Check DTC Status

(1)	Connect scantool to Data Link Connector(DLC).

(2)

IG "ON".

(3)	Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.

(4)	Read "DTC Status" parameter.

(5)

Is parameter displayed "Present fault"?

	▶ Go to "Terminal and connector inspection" procedure.
	▶ Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

Terminal And Connector Inspection

1.	Many malfunctions in the electrical system are caused by poor harness and terminal condition. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

	▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure
	▶ Go to "Signal Circuit Inspection" procedure.

Signal Circuit Inspection

■ Check Voltgae

1.	IG "OFF" and disconnect ETC Motor & TPS connector.

2.	IG "ON" and ENG "OFF"

Measure voltage between TPS1 signal terminal of ETC Motor & TPS harness connector and chassis ground.

Specification : Approx. 5V

Is the measured voltage within specification?

	▶ Go to "Check short to battery in harness" as follows.
	▶ Go to "Check open in harness" as follows.

■ Check Open In Harness

1.	IG "OFF" and disconnect ETC Motor & TPS connector and PCM connector.

Measure resistance between TPS1 signal terminal of ETC Motor & TPS harness connector and TPS1 signal terminal of PCM harness connector.

Specification : Below 1Ω

Is the measured resistance within specification?

	▶ Go to "Ground Circuit Inspection" procedure.
	▶ Repair open in harness, and go to "Verification of Vehicle Repair" procedure.

■ Check Short To Battery In Harness

1.	IG "OFF" and disconnect ETC Motor & TPS connector and PCM connector.

2.	Measure resistance between TPS1 signal and TPS1 power terminals of ETC Motor & TPS harness connector.(Measurement "A")

3.	Measure resistance between TPS1 signal and TPS2 power terminals of ETC Motor & TPS harness connector.(Measurement "A")

4.	Measure resistance between TPS1 signal and ETC motor(+) terminals of ETC Motor & TPS harness connector.(Measurement "B")

Measure resistance between TPS1 signal and ETC motor(-) terminals of ETC Motor & TPS harness connector.(Measurement "B")

Specification : Infinite

Is the measured resistance within specification?

	▶ Go to "Ground circuit inspection " procedure.
	▶ Repair short to battery in harness, and go to "Verification of Vehicle Repair" procedure.

Ground Circuit Inspection

■ Check Open In Harness

1.	IG "OFF" and disconnect ETC Motor & TPS connector.

2.	IG "ON" and ENG "OFF"

3.	Measure voltage between TPS1 power terminal of ETC Motor & TPS harness connector and chassis ground.(Measurement "A")

Measure voltage between TPS1 power and TPS1 ground terminals of ETC Motor & TPS harness connector.(Measurement "B")

Specification : Voltage difference between measurement "A" and "B" is below 200mV.

Is the measured voltage within specification?

	▶ Go to "Component inspection" procedure.
	▶ Repair open or contact resistance in harness, and go to "Verification of Vehicle Repair" procedure.

Component Inspection

■ Check TPS Resistance

1.	IG "OFF" and disconnect ETC Motor & TPS connector.

Measure resistance between TPS1 power and TPS1 ground terminals of ETC Motor & TPS connector.(component side)

Specification : 4 ~ 6kΩ

Is the measured resistance within specification?

	▶ Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
	▶ Substitute with a known - good ECT motor & TPS and check for proper operation. If the problem is corrected, replace ECT motor & TPS and go to "Verification of Vehicle Repair" procedure.

Procedure of ETS Initialization

1.	Erase the trouble codes on PCM

2.	Turn the ignition key off and keep this condition until the main relay is turned off.(10 sec.)

3.	Turn ignition key on more than 1second to record the throttle motor position on the EEPROM.

Verification Of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.

1.	Connect scantool and select "DTC" button.

2.	Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions

3.	Read "DTC Status" parameter

Is parameter displayed "History(Not Present) fault"?

	▶ System performing to specification at this time. Clear the DTC
	▶ Go to the applicable troubleshooting procedure.