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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
  • 12V starter 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 higher than -0.04 volt.
Judgment Criterion
  • The target throttle position sensor (main) voltage subtracted from the throttle position sensor (main) output voltage is higher than 0.5 volt for 0.4 second.
Check Conditions
  • 12V starter 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) voltage is lower 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
  • 12V starter 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 volt or higher for 0.4 second.
Check Condition
  • 12V starter 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 Diagnosis 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 the throttle actuator control motor.
(1) Disconnect the throttle body assembly connector and measure at throttle body assembly side.
(2) Measure the resistance between throttle body assembly side connector terminal ETV+ and ETV-.
Standard value: 0.3 - 100 ohms [at 20°C (68°F)]
Is the measured resistance between 0.3 and 100 ohms [at 20°C (68°F)]?
Go to Step 2.
Replace the throttle body assembly. Then go to Step 5.
 
STEP 2. 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 3.
Repair the connector(s) or wiring harness. Then go to Step 5.
 
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 the connector(s) or wiring harness. Then go to Step 5.
 
STEP 4. Check the trouble symptoms.
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(3) Check the diagnostic trouble code (DTC).
Is DTC P0638 set?
Replace the ECM (Refer to Removal and Installation ). Then go to Step 5.
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 5. Test the OBD-II drive cycle.
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(3) Check the diagnostic trouble code (DTC).
Is DTC P0638 set?
Retry the troubleshooting.
The inspection is complete.