P0638

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. The throttle body contains the actuator, the throttle plate and the throttle position sensor (potentiometer), which are integrated in one housing. The actuator consists of a DC motor with a two-stage gear. The opening angle of the throttle valve is detected by the throttle position sensor which is mounted on the throttle body. And it provides feedback to the ECM 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 TPS every 8.5 sec. under detecting condition, if the difference between real and target throttle position is above the specified value, PCM sets P0638 and then MIL(Malfunction Indication Lamp) turns on.

DTC DETECTING CONDITION





SIGNAL WAVEFORM





SPECIFICATION





SCHEMATIC DIAGRAM





MONITOR DTC STATUS

1. Check DTC Status
(1) Connect scantool to Data Link Connector(DLC).
(2) IG "ON".
(3) Select "Diagnostic Trouble Codes(DTCs)" mode, and then Press F4(DTAL) to check DTC's information from the DTCs menu
(4) Read "DTC Status" parameter.




(5) Is parameter displayed "Present fault"?
YES
> Go to "Terminal and connector inspection" procedure.
NO
> 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 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.
3. Has a problem been found?
YES
> Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO
> Go to " Control Circuit Inspection " procedure.

CONTROL CIRCUIT INSPECTION

1. Check voltage
(1) IG "OFF".
(2) Disconnect ETS motor & TPS connector.
(3) IG "ON" and ENG "OFF"
(4) Measure the voltage between terminal 5,8 of ETS motor & TPS harness connector and chassis ground.

Specification : Approx. 12V





(5) Is the measured voltage within specification?
YES
> Go to "Component inspection" procedure.
NO
> Go to "Check open in harness" as follows.
2. Open in control circuit inspection
(1) IG "OFF"
(2) Disconnect ETS motor & TPS connector and PCM connector.
(3) Measure the resistance between terminal 5 of ETS motor & TPS harness connector and terminal C201-2 (2) of PCM harness connector.
(4) Measure the resistance between terminal 8 of ETS motor & TPS harness connector and terminal C201-2 (1) of PCM harness connector.

Specification : Approx. below 1Ohms





(5) Is the measured resistance within specification ?
YES
> Go to "Component inspection" procedure.
NO
> Repair Open in motor harness and go to "Verification of Vehicle Repair" procedure.

COMPONENT INSPECTION

1. Check throttle valve for stuck
(1) IG "OFF".
(2) Disconnect the air hose between throttle body and air mass flow sensor.
(3) Check stuck on throttle valve.
(4) Is the throttle valve normal?
YES
> Go to check "ETS motor resistance" as follows.
NO
> Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
2. Check ETS motor resistance
(1) IG "OFF".
(2) Disconnect ETS motor & TPS connector.
(3) Measure the resistance between terminal 5 and 8 of ETS motor & TPS connector(component side).

Specification : Approx. 1.275 - 1.725Ohms @ 23°C (73.4°F)





(4) Is the measured resistance within specification?
YES
> Go to "ETC motor actuation test" procedure.
NO
> 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
1. Erase the trouble codes on PCM
2. Turn the ignition key off and keep this condition until the main relay is turned off.(It will takes 10 second)
3. Turn ignition key on more than 1second to record the throttle motor position on the EEPROM
3. ETC motor actuation test
(1) IG "OFF".
(2) Connect ETS motor & TPS connector.
(3) After IG "ON", execute the "ETC motor actuation test" by Scantool.




(4) Does the "ETC motor actuation test" execute normally?
YES
> 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.
NO
> 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
1. Erase the trouble codes on PCM
2. Turn the ignition key off and keep this condition until the main relay is turned off.(It will takes 10 second)
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. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions
4. Monitor that all rediness test have been verified as " Complete "
5. Are any DTCs present ?
YES
> Go to the applicable troubleshoooting procedure.
NO
> System is performing to specification at this time.