P0638
DTC P0638
GENERAL DESCRIPTION
ETC (Electronic Throttle Control Valve) is the device controlling amount of air to engine according to driver's intension. Different from the existing mechanical throttle valve which is composed of accelerator pedal and connecting wire cable, ETC consists of a motor, a throttle body and a throttle position sensor. Receiving input signals from electronic accelerator pedal module, PCM lets ETC motor control throttle valve. With ETC, cruise control system works without any additional device.
DTC DESCRIPTION
Checking output signals from TPS under detecting condition, if the difference between real and target throttle position is above the specified value, PCM sets P0638. MIL(Malfunction Indication Lamp) turns on.
DTC Detecting Condition:
DTC DETECTING CONDITION
Specification:
SPECIFICATION
Schematic Diagram:
SCHEMATIC DIAGRAM
SIGNAL WAVEFORM AND DATA
MONITOR SCANTOOL DATA
1. Ignition "OFF"
2. Connect Scantool and Engine "ON"
3. Monitor "ETS Motor" items on Current Data
4. Are those related current data displayed correctly?
YES - Fault is intermittent caused by poor contact in Sensor`s and/or PCM`s connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection,bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and goto "Verification of Vehicle Repair" procedure
NO - Go to "Terminal and Connector Inspection" 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
a. IG "OFF".
b. Disconnect ETS motor& TPS connector.
c. IG "ON" and ENG "OFF"
d. Measure the voltage between terminal 2,3 of ETS motor& TPS harness connector and chassis ground.
Specification : Approx. 12 V
e. 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
a. IG "OFF"
b. Disconnect ETS motor& TPS connector and PCM connector.
c. Measure the resistance between terminal 2 of ETS motor& TPS harness connector and terminal 2 of PCM harness connector.
d. Measure the resistance between terminal 3 of ETS motor& TPS harness connector and terminal 1 of PCM harness connector.
Specification : Approx. below 1 ohm.
e. 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
a. IG "OFF".
b. Disconnect the air hose between throttle body and air mass flow sensor.
c. Check throttle valve for stuck.
d. 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
a. IG "OFF".
b. Disconnect ETS motor& TPS connector.
c. Measure the resistance between terminal 2 and 3 of ETS motor& TPS connector (component side).
Specification : Approx. 1.275 - 1.725 ohms @ 23 °C (73.4 °F)
d. 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 seconds)
3. Turn ignition key on more than 1 second to record the throttle motor position on the EEPROM
3. ETC motor actuation test
a. IG "OFF".
b. Connect ETS motor& TPS connector.
c. After IG "ON", execute the "ETC motor actuation test" by Scantool.
d. 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 seconds)
3. Turn ignition key on more than 1 second to record the throttle motor position on the EEPROM
3. Turn ignition key on more than 1 second 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 readiness test have been verified as "Complete".
5. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.