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DTC P0638: Throttle Actuator Control Motor Circuit Range/Performance Problem
 
 
 
 
THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE PROBLEM CIRCUIT
Refer to DTC P2101 - Throttle Actuator Control Motor Magneto Malfunction .
 
 
CIRCUIT OPERATION
Refer to DTC P2101 - Throttle Actuator Control Motor Magneto Malfunction .
 
 
TECHNICAL DESCRIPTION
ECM checks the electronic controlled throttle system for abnormal conditions.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • Difference between throttle position sensor (main) output and target opening is greater than the specified value.
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
DTC SET CONDITIONS
Check Conditions
  • Battery positive voltage is higher than 8.3 volts.
  • Throttle position sensor (main) output voltage is between 0.2 and 4.8 volts.
  • Drop of throttle position sensor (main) output voltage per 100 milliseconds is more than -0.04 volt.
Judgment Criterion
  • The target throttle position sensor (main) voltage subtracted from the throttle position sensor (main) output voltage is more than 0.5 volt for 0.4 second.
Check Conditions
  • Battery positive voltage is higher than 8.3 volts.
  • Throttle position sensor (main) output voltage is between 0.2 and 4.8 volts.
  • Target throttle position sensor (main) output voltage is less than 1.5 volts.
Judgment Criterion
  • Difference between throttle position sensor (main) output voltage and target throttle position sensor (main) voltage is 0.6 volt or higher for 0.4 second.
Check Conditions
  • Battery positive voltage is higher than 8.3 volts.
  • Throttle position sensor (main) output voltage is between 0.2 and 4.8 volts.
Judgment Criterion
  • Difference between throttle position sensor (main) output voltage and target throttle position sensor (main) voltage is 1.5 volt or higher for 0.4 second.
Check Condition
  • Battery positive voltage is higher than 8.3 volts.
Judgment Criterion
  • Throttle position sensor (main) default opening learnt value is 4 volts or higher.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Throttle opening degree position is in default position.
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
  • Throttle valve return spring failed.
  • Throttle valve operation failed.
  • Throttle actuator control motor failed.
  • Throttle actuator control motor circuit harness damage, or connector damage.
  • ECM failed.

 
 
DIAGNOSIS
STEP 1. Check throttle body.
Check whether the throttle valve return spring is normal.
Is the check result normal?
Go to Step 2.
Replace the throttle body assembly. Then go to Step 6.
 
STEP 2. Check the throttle actuator control motor.
Refer to Throttle Actuator Control Motor Check .
Is the measured resistance between 0.3 and 100 ohms [at 20°C (68°F)]?
Go to Step 3.
Replace the throttle body assembly. Then go to Step 6.
 
STEP 3. Check of harness damage in ETV+ line between throttle body assembly connector and ECM connector.
Is the harness wire in good condition?
Go to Step 4.
Repair it. Then go to Step 6.
 
STEP 4. Check of harness damage in ETV- line between throttle body assembly connector and ECM connector.
Is the harness wire in good condition?
Go to Step 5.
Repair it. Then go to Step 6.
 
STEP 5. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0638 set?
Replace the ECM (Refer to Removal and Installation ). Then go to Step 6.
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
 
STEP 6. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0638 set?
Retry the troubleshooting.
The inspection is complete.