P0446
DTC P0446: Evaporative Emission Control System Vent Control CircuitEvaporative Emission Ventilation Solenoid Circuit (Part 1):
Evaporative Emission Ventilation Solenoid Circuit (Part 2):
CIRCUIT OPERATION
- The evaporative emission ventilation solenoid power is supplied from the MFI relay (terminal No. 2).
- The ECM controls the evaporative emission ventilation solenoid ground by turning the power transistor in the ECM ON and OFF.
TECHNICAL DESCRIPTION
- To judge if there is open circuit in the evaporative emission ventilation solenoid drive circuit, ECM measures the surge voltage of the evaporative emission ventilation solenoid coil.
- The ECM drives the evaporative emission ventilation solenoid. After the solenoid is turned off, the ECM will check if the solenoid coil produces a surge voltage (battery positive voltage + 2 volts).
DESCRIPTIONS OF MONITOR METHODS
Off-surge does not occur after solenoid is operated on to off.
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
Logic Flow Chart
Logic Flow Chart:
Check Conditions
- Engine is being cranked.
- Battery positive voltage is between 10 and 16.5 volts.
Judgement Criteria
- The evaporative emission ventilation solenoid coil surge voltage (battery positive voltage + 2 volts) is not detected for 0.2 second.
- The ECM monitors for this condition once during the drive cycle.
Check Conditions
- Battery positive voltage is between 10 and 16.5 volts.
- ON duty cycle of the evaporative emission purge solenoid is 0 percent.
- Evaporative emission ventilation solenoid is ON.
- 1 second or more has elapsed after the above mentioned conditions have been met.
Judgement Criterion
- The evaporative emission ventilation solenoid coil surge voltage (battery positive voltage + 2 volts) is not detected for 1 second after the evaporative emission ventilation solenoid is turned OFF.
FAIL-SAFE AND BACKUP FUNCTION
- None
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 23. OBD- II Drive Cycle
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Evaporative emission ventilation solenoid failed.
- Open or shorted evaporative emission ventilation solenoid circuit, harness damage, or connector 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
- MB992110: Power Plant ECU Check Harness
STEP 1. Using scan tool MB991958, check actuator test item 15: Evaporative Emission Ventilation Solenoid.
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. Set scan tool MB991958 to the actuator test mode for item 15, Evaporative emission ventilation solenoid.
- An operation sound should be heard and vibration should be felt when the evaporative emission ventilation solenoid is operated.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the solenoid operating properly?
YES : It can be assumed that this malfunction is intermittent.
NO : Go to Step 2.
STEP 2. Check harness connector F-23 at the evaporative emission ventilation solenoid for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 3.
NO : Repair or replace it. Then go to Step 10.
STEP 3. Check the evaporative emission ventilation solenoid.
1. Disconnect the evaporative emission ventilation solenoid connector F-23.
2. Measure the resistance between evaporative emission ventilation solenoid side connector terminal No. 1 and No. 2.
Standard value: 17 - 21 Ohms [at 20°C (68°F)]
Q: Is the measured resistance between 17 and 21 Ohms [at 20°C (68°F)]?
YES : Go to Step 4.
NO : Replace it. Then go to Step 10.
STEP 4. Measure the power supply voltage at evaporative emission ventilation solenoid harness side connector F-23.
1. Disconnect the connector F-23 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 2 and ground.
- Voltage should be battery positive voltage.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts) present?
YES : Go to Step 6.
NO : Go to Step 5.
STEP 5. Check harness connector A-34X at MFI relay for damage.
Q: Is the harness connector in good condition?
YES : Check harness connectors C-43, C-47 and D-16 at intermediate connectors for damage, and repair or replace as required. Then go to Step 10.
NO : Repair or replace it. Then go to Step 10.
STEP 6. Check harness connector B-10 at ECM for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 7.
NO : Repair or replace it. Then go to Step 10.
STEP 7. Measure the power supply voltage at ECM connector B-10 by using power plant ECU check harness special tool MB992110.
1. Disconnect all ECM connectors. Connect the power plant ECU check harness special tool MB992110 between the separated connectors.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 117 and ground.
- Voltage should be battery positive voltage.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts) present?
YES : Go to Step 8.
NO : Check harness connectors C-47 and D-16 at intermediate connectors for damage, and repair or replace as required. Then go to Step 10.
STEP 8. Check for harness damage between MFI relay connector A-34X (terminal No. 2) and evaporative emission ventilation solenoid connector F-23 (terminal No. 2).
NOTE: Check harness after checking intermediate connectors C-43, C-47 and D-16. If intermediate connectors are damaged, repair or replace them. Then go to Step 10.
Q: Is the harness wire in good condition?
YES : Go to Step 9.
NO : Repair it. Then go to Step 10.
STEP 9. Check for harness damage between evaporative emission ventilation solenoid connector F-23 (terminal No. 1) and ECM connector B-10 (terminal No. 117).
NOTE: Check harness after checking intermediate connectors C-47 and D-16. If intermediate connectors are damaged, repair or replace them. Then go to Step 10.
Q: Is the harness wire in good condition?
YES : Replace the ECM. When the ECM is replaced, register the ID code. Then go to Step 10.
NO : Repair it. Then go to Step 10.
STEP 10. 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 23. OBD- II Drive Cycle
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0446 set?
YES : Retry the troubleshooting.
NO : The inspection is complete.