P0446
DTC P0446: Evaporative Emission Control System Vent Control Circuit
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
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.
- More than 1 second 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.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22 Monitors, Trips, Drive Cycles and Readiness Codes.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Evaporative emission ventilation solenoid failed.
- Harness damage
- 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
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. How to Cope With Intermittent Malfunctions.
NO Go to Step 2.
STEP 2. Check harness connector A-33X at the MFI relay connector and harness connector B-11 at the ECM for damage.
Q. Is the harness connector in good condition?
YES Go to Step 3.
NO Repair it. Harness Connector Inspection.
Then go to Step 7.
STEP 3. Check the evaporative emission ventilation solenoid.
(1)Disconnect the evaporative emission ventilation solenoid connector D-116.
(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 7.
STEP 4. Measure the power supply voltage at the evaporative emission ventilation solenoid connector D-116.
(1)Disconnect the evaporative emission ventilation solenoid connector D-116 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 the measured voltage battery positive voltage?
YES Go to Step 5.
NO Repair it. Then go to Step 7.
STEP 5. Check for open circuit and short circuit to ground and harness damage between the evaporative emission ventilation solenoid connector D-116 and the ECM connector B-11.
(1)Disconnect the evaporative emission ventilation solenoid connector D-116 and the ECM connector B-11.
(2)Measure the evaporative emission ventilation solenoid connector D-116 (terminal No. 1) and the ECM connector B-11 (terminal No. 117).
- Should be less than 2 ohms.
(3)Check for the evaporative emission ventilation solenoid connector D-116 (terminal No.
1) and ground.
- Not continuity.
Q. Is the harness wire in good condition?
YES Go to Step 6.
NO Repair it. Then go to Step 7.
STEP 6. Check the trouble symptoms.
(1)Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22 Monitors, Trips, Drive Cycles and Readiness Codes.
(2)Check the diagnostic trouble code (DTC).
Q. Is DTC P0446 set?
YES Replace the ECM. When the ECM is replaced, register the ID code. Refer to ID registration procedure manual - ID codes registration judgement table [Vehicles with KOS] or ID registration procedure manual - ID codes registration judgement table [Vehicles with WCM]. Then go to Step 7.
NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
STEP 7. 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 22 Monitors, Trips, Drive Cycles and Readiness Codes.
(2)Check the diagnostic trouble code (DTC).
Q. Is DTC P0446 set?
YES Retry the troubleshooting.
NO The inspection is complete.