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DTC P1401: Evaporative Emission Leak Detection Pump Pulsation
 
 
 
 
TECHNICAL DESCRIPTION
  • During the key-off evaporative leakage monitoring, when pulsation is observed in evaporative emission canister pressure while the evaporative emission leak detection pump is operating, it is judged as an evaporative emission leak detection pump pulsation failure.
 
 
MONITOR EXECUTION
  • Once per driving cycle.
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • Evaporative emission purge solenoid monitor
  • Bypass valve monitor
  • Fuel tank solenoid valve monitor
  • Switching valve monitor
  • Canister pressure sensor monitor
  • Manifold absolute pressure sensor monitor
  • Fuel tank pressure sensor monitor
  • Fuel tank differential pressure sensor monitor
  • Barometric pressure sensor/Manifold absolute pressure correlation
  • Barometric pressure sensor monitor
  • Fuel level sensor monitor
  • Engine off timer monitor
  • Controller area network (CAN) monitor
Sensor (The sensor below is determined to be normal)
  • Engine coolant temperature sensor
  • Intake air temperature sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart
Check Conditions
  • Power supply mode of electric motor switch is OFF.
  • 12V starter battery positive voltage is 11 volts or higher.
  • Engine coolant temperature is higher than 4°C (39°F) and lower than 35°C (95°F).
  • Intake air temperature at ECM wake-up is higher than 4°C (39°F) and lower than 35°C (95°F).
  • ECM is woken up in 5, 6 or 8.5 hours since the power supply mode of electric motor switch was OFF.
  • Barometric pressure is 76 kPa (22.4 in.Hg) or higher.
  • Fuel level is 85 % or less.
  • Fuel tank pressure at ECM wake-up is less than 19.96 kPa (5.89 in.Hg) or more than 40.00 kPa (11.81 in.Hg).
Judgment Criteria
  • The minimum canister pressure subtracted from maximum canister pressure is more than 0.358 kPa (0.1057 in.Hg).
  • The ECM monitors for this condition for 3 cycles of 9 seconds each during drive cycles.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 3 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Evaporative emission leak detection pump pulsation
  • Evaporative emission leak detection pump circuit harness damage or connector damage.
  • ECM failed.

 
 
DIAGNOSIS
STEP 1. Check of harness damage in EVB line between evaporative leak check module connector and ECM connector.
Is the harness wire in good condition?
Go to Step 2.
Repair the connector(s) or wiring harness. Then go to Step 4.
 
STEP 2. Check of harness damage in E line between evaporative leak check module connector and ground.
Is the harness wire in good condition?
Go to Step 3.
Repair the connector(s) or wiring harness. Then go to Step 4.
 
STEP 3. Replace the evaporative emission leak detection pump (integrated in evaporative emission canister).
(1) Replace the evaporative emission leak detection pump (integrated in evaporative emission canister).
(2) Carry out an evaporative emission system monitor. Refer to Evaporative Emission System Monitor Test .
(3) Check the item 188, Pump Pulsation in the data list.
(4) Turn off the power supply mode of the electric motor switch.
Is the data list "Normal"?
The inspection is complete.
Replace the ECM (Refer to Removal and Installation ). Then go to Step 4.
 
STEP 4. Test the OBD-II drive cycle.
(1) Carry out test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 3 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P1401 set?
Retry the troubleshooting.
The inspection is complete.