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 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.
DTC DETECTING CONDITION
** If Main relay has a fault(ex. Open) while the engine is running, the DTCs,P0638/P0685/P1295/P2106, can happen at the same time.
- P0638 Throttle Actuator Control Range/Performance(Bank 1)
- P0685 ECM/PCM Power Relay Control Circuit /Open
- P1295 Throttle Actuator Control System - Power Management
- P2106 Throttle Actuator Control System - Forced Limited Power
SIGNAL WAVEFORM AND DATA
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 F5(INFO) to check DTC's information from the DTCs menu
(4) Read "DTC Status" parameter.
(5) Is "Present" Fault displayed?
YES
> Go to "Terminal and connector inspection" procedure.
NO
> 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 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.
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 2,3 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. Check open in harness
(1) IG "OFF"
(2) Disconnect ETS motor & TPS connector and ECM connector.
(3) Measure the resistance between terminal 2 of ETS motor & TPS harness connector and terminal 2 of ECM harness connector(C144-A).
(4) Measure the resistance between terminal 3 of ETS motor & TPS harness connector and terminal 1 of ECM harness connector(C144-A).
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 for sticking throttle valve
(1) IG "OFF".
(2) Disconnect the air hose between throttle body and air mass flow sensor.
(3) Check for sticking 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 2 and 3 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 ECM
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
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 ECM and check for proper operation. If the problem is corrected, replace ECM 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 ECM
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 scan tool and select "Diagnostic Trouble Codes(DTCs)" mode
2. Press F5(INFO) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
3. Read "DTC Status" parameter
4. Is "History (Not Present)" fault displayed?
YES
> System performing to specification at this time. Clear the DTC
NO
> Go to the applicable troubleshooting procedure.