P0638
DTC P0638: Throttle Actuator Control Motor Circuit Range/Performance ProblemTHROTTLE ACTUATOR CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE PROBLEM CIRCUIT
Throttle Actuator Control Motor Circuit (Part 1):
Throttle Actuator Control Motor Circuit (Part 2):
CIRCUIT OPERATION
- Controls the current that is applied from the ECM (terminals No. 15, No. 16) to the throttle actuator control motor (terminals No. 1, No. 2)
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.
Judgement 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.
Judgement 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.
Judgement 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.
Judgement Criterion
- Throttle position sensor (main) default opening learnt value is higher than 4 volts or higher.
OBD-II DRIVE CYCLE PATTERN
None.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Throttle actuator control motor failed.
- Connector damage.
- Harness damage.
- ECM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
STEP 1. Check harness connector B-08 at throttle actuator control motor and harness connector B-10 at ECM for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 2.
NO : Repair or replace it. Refer to General (Electrical), Harness Connector Inspection. Then go to Step 5.
STEP 2. Check the throttle actuator control motor.
1. Disconnect the connector B-08.
2. Measure the resistance between throttle actuator control motor side connector terminal No. 1 and No. 2.
Standard value: 0.3 - 80 ohms [at 20 °C (68 °F)]
Q: Is the measured resistance between 0.3 and 80 ohms [at 20 °C (68 °F)]?
YES : Go to Step 3.
NO : Replace the throttle body assembly. Then go to Step 5.
STEP 3. Check for harness damage between throttle actuator control motor connector B-08 and ECM connector B-10.
1. Disconnect the connector B-08 and B-10 measure at the harness side.
2. Measure the resistance between B-08 connector and B-10 connector.
a. Connector B-08 (terminal No. 1) and connector B-10 (terminal No. 15).
b. Connector B-08 (terminal No. 2) and connector B-10 (terminal No. 16).
- Should be less than 2 ohms.
Q: Is the measured resistance less than 2 ohms?
YES : Then go to Step 4.
NO : Repair it. Then go to Step 5.
STEP 4. Using scan tool MB991958, read the diagnostic trouble code (DTC).
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
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.
Q: Is DTC P0638 set?
YES : Replace the ECM. When the ECM is replaced, register the ID code. Refer to Diagnosis - ID Codes Registration Judgment Table [Vehicles with KOS] or Diagnosis-ID Codes Registration Judgment Table [Vehicles with WCM]. Then go to Step 5.
NO : It can be assumed that this malfunction is intermittent. Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.
STEP 5. Using scan tool MB991958, read the diagnostic trouble code (DTC).
1. Connect scan tool MB991958 to the data link connector.
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.
Q: Is DTC P0638 set?
YES : Retry the troubleshooting.
NO : The inspection is complete.