P0638 Throttle Actuator Control Range/Performance (Bank 1) - 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 TPS under detecting condition, if the difference between real and target throttle position is above the specified value, ECM sets P0638 and then MIL(Malfunction Indication Lamp) turns on.

Comparing real intake air flow and the intake air flow calculated by ETS under detecting condition, if the air flow more than threshold value is detected for more than 19 sec., ECM sets P0638.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Case1

Monitor the throttle position

(Case1)

1.	Throttle stuck

2.	Open in motor circuit

3.	Faulty motor

4.	Faulty ECM

(Case2)

1.	Air Leakage between TPS and MAP

2.	Faulty throttle body or intake manifold

3.	Faulty MAPS

Case2

Monitor the measured engine airflow and the estimated airflow

Enable Conditions

Case1

Engine running

No faults present

Case2

Engine works

Battery voltage >5V

Threshold value

Case1

The difference between the real ETS motor & TPS value and the target ETS motor & TPS value is over 4.5°.

When real Throttle position is below 36°, (the real throttle position – the target throttle position) < – 4.5°

(the real throttle position – the target throttle position) < – 18°

Case2

MAPS reading – ETC estimated airflow > 9 g/s

Diagnosis Time

Continuous

MIL On Condition

1 driving cycle

※ If Main relay has a fault(ex. Open) under engine running, the DTCs, P0638/P0685/P1295/P2106, can happen at the same time.

– P0638 Throttle Actuator Control Range/Performance(Bank 1)

– P0685 ECM/ECM Power Relay Control Circuit /Open

– P1295 Throttle Actuator Control System – Power Management

– P2106 Throttle Actuator Control System – Forced Limited Power

SPECIFICATION

TPS
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

MAP
Pressure(kPa)	Voltage(V)
20	0.79
46.66	1.84
101.32	4.0

DIAGNOSTIC CIRCUIT DIAGRAM

SIGNAL WAVEFORM & DATA

Fig.1) Normal waveform of ETC motor at acceleration

Fig.2) Normal waveform of ETC motor at deceleration

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 and go to “Verification of Vehicle Repair” procedure
	▶ Go to ” Control Circuit Inspection ” procedure.

CONTROL CIRCUIT INSPECTION

■ Check voltage

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

IG “ON”

Measure the voltage between ETC motor(+)/(-) of ETC Motor & TPS harness connector and chassis ground.

Approx. B+

Is the measured voltage within specification ?

	▶ Go to “Component Inspection” procedure.
	▶ Go to “Check open in harness” as follows.

■ Check open in harness

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

2.	Measure the resistance between ETC motor (+) terminal of ETC Motor & TPS harness connector and ETC motor (+) terminal of ECM harness connector.

Measure the resistance between ETC motor (-) terminal of ETC Motor & TPS harness connector and ETC motor (-) terminal of ECM harness connector.

Approx. below 1Ω

Is the measured resistance within specification ?

	▶ Go to “System Inspection” procedure.
	▶ Repair open in motor harness

SYSTEM INSPECTION

■ Visual Inspection

1.	Check the installation condition between MAPS and throttle body.

2.	Check deforamtion, crack or installation of throttle valve(body)

Has a problem been found ?

	▶ Repair or replace as necessary and go to “Verification of Vehicle Repair” procedure.
	▶ Go to “Check MAPS” as follows.

■ Check MAPS

1.	IG “OFF” and install a GDS.

2.	Connect probe to MAPS and TPS to check signal waveform by using oscilloscope function.

ENG “ON” and monitor signal waveform during accelleration and decelleration.

Signal waveform will be displayed as follows.

Pressure(kPa)	Voltage(V)
20	0.79
46.66	1.84
101.32	4.0

Is the relationship between the MAP and the TPS correct?

	▶ Go to “Component Inspection” procedure.
	▶ Substitute with a known – good MAPS and check for proper operation. If the problem is corrected, replace MAPS

COMPONENT INSPECTION

■ Check throttle valve for stuck

1.	IG “OFF” and disconnect the air hose between throttle body and air mass flow sensor.

2.	Check stuck on throttle valve..

Is the throttle valve normal?

	▶ Go to “Check ETC motor resistance” as follows.
	▶ Repair or replace as necessary and go to “Verification of Vehicle Repair” procedure.

■ Check ETC motor resistance

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

Measure the resistance between ETC motor(+) and (-) terminals of ETC Motor & TPS connector (component side).

Approx. 1.275 ~ 1.725Ω @ 23°C(73.4°F)

Is the throttle valve normal?

	▶ Is the measured resistance within specification ?
	▶ Substitute with a known – good ETC motor and check for proper operation. If the problem is corrected, replace ETC motor and go to “Verification of Vehicle Repair” procedure.

※ 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

■ ETC motor actuation test

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

2.	After IG “ON”, execute the “ETC motor actuation test” by Scantool.

Is the measured resistance within specification ?

▶ Substitute with a known – good ECM and check for proper operation. If the problem is corrected, replace ECM and go to “Verification of Vehicle Repair” procedure.

There is a memory reset function on scantool that can erase optional parts automaticallydetected 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 ETC motor and check for proper operation. If the problem is corrected, replace ETC motor and go to “Verification of Vehicle Repair” procedure.

※ 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

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