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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 stored 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
  • Throttle position sensor (main) output voltage has continued to be higher than the target throttle position sensor (main) voltage by 0.5 volt or more 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 1.5 volts or lower.
Judgment Criteria
  • 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 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 higher than 4 volts or higher.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Throttle opening degree position is in default position.
 
 
OBD-II DRIVE CYCLE PATTERN
  • None
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be stored are: )
  • Throttle actuator control motor failed.
  • Connector damage.
  • Harness damage.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle Communication Interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite Main Harness A
  • MB992747: V.C.I.-Lite USB Cable Short
  • MB992748: V.C.I.-Lite USB Cable Long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
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+ line and ETV- line.
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 it. 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 it. Then go to Step 5.
 
STEP 4. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Turn the ignition switch to the "ON" position.
(3) After the DTC has been deleted, read the DTC again.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC P0638 stored?
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. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Turn the ignition switch to the "ON" position.
(3) After the DTC has been deleted, read the DTC again.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC P0638 stored?
Retry the troubleshooting.
The inspection is complete.