P0122 Throttle Position Sensor 1 Signal Circuit Low Input - Automotive Repair Guides & Equipment

COMPONENT LOCATION

GENERAL DESCRIPTION

The Electronic Throttle Control(ETC) system consists of the 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 ECM controls the throttle motor to open and close the throttle valve. The 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. The TPS provides feedback to the ECM to control the throttle motor in order to control the throttle valve opening angle properly in response to the driver’s demands.

DTC DESCRIPTION

Checking output signals from TPS1 every 8.5 sec. under detecting condition, if an output signal is below 0.25V for more than 0.1 sec., ECM sets P0122.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible Cause

DTC Strategy

Signal low

1.	Poor connection

2.	Open or short to ground in power harness

3.	Short to ground in signal harness

TPS

ECM

Enable Conditions

IG “ON”

Threshold value

The voltage of TPS < 0.25V

Diagnosis Time

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

MIL On Condition

1 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

DIAGNOSTIC CIRCUIT DIAGRAM

SIGNAL WAVEFORM & DATA

Fig.1) Normal data & waveform of TPS1 & TPS2 with no accel pedal depressed under IG ON condition

Fig.2) Normal data & waveform of TPS1 & TPS2 with accel pedal depressed under IG ON condition

Fig.3) Abnormal data of TPS1 & TPS2 under open condition

MONITOR GDS DATA

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

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.

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 ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary

TERMINAL AND CONNECTOR INSPECTION

1.	Many malfunctions in the electrical system are caused by poor harness and terminals. 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.
	▶ Go to ” Power Circuit Inspection ” procedure.

POWER CIRCUIT INSPECTION

■ Check voltage

1.	IG “OFF” and disconnect ETC Motor & TPS connector.

IG “ON”.

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

Approx. 5V

Is the measured voltage within specification ?

	▶ Go to “Signal circuit inspection” procedure.
	▶ Repair open or short to ground in power harness,

SIGNAL CIRCUIT INSPECTION

■ Check short to ground in harness

1.	IG “OFF” and disconnect ETC Motor & TPS connector and ECM connector.

2.	Measure resistance between TPS1 signal terminal of ETC Motor & TPS harness connector and chassis ground.(Measurement “A”)

Measure resistance between TPS1 signal and TPS ground terminals of ETC Motor & TPS harness connector.(Measurement “B”)

Infinite

Is the measured resistance within specification ?

	▶ Go to “Component inspection” procedure.
	▶ Repair short to ground in harness

COMPONENT INSPECTION

■ Check TPS resistance

1.	IG “OFF” and disconnect ETC Motor & TPS connector.

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

1.6 ~ 2.4kΩ

Is the measured resistance within specification ?

▶ Substitute with a known – good ECM and check for proper operation. If the problem is corrected, replace ECM .

There is a memory reset function on GDS that can erase optional parts automatically detected and memorized by ECM. Before or after testing ECM on the vehicle, use this function to reuse the ECM on the others

▶ Substitute with a known – good ECT motor & TPS and check for proper operation. If the problem is corrected, replace ECT motor & TPS

※ Procedure of ETS Initialization

Erase the trouble codes on ECM

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

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

New Videos on our YouTube Channel Every Week, Subscribe Now!

Related Posts