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DTC P1446: Bypass Valve Circuit High Input

 
 
 
 
CIRCUIT OPERATION
  • The bypass valve power is supplied from the MFI relay.
  • The ECM controls ground bypass valve by turning the power transistor in the ECM "ON" and "OFF".
 
 
TECHNICAL DESCRIPTION
  • In response to a signal from the ECM, the bypass valve shuts off or opens the path between the purge line and the evaporative emission canister.
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • Powertrain control module (PCM) monitor
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
DTC SET CONDITIONS
Logic Flow Chart
Check Conditions
  • More than 2 seconds have passed since the power supply mode of electric motor switch was ON.
  • 12V starter battery positive voltage is between 10 and 16.5 volts.
Judgment Criterion
  • The coil current is 2 amperes or higher with the bypass valve driving for 2 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Fuel filler lid cannot be opened even when pressing the fuel filler lid opener switch.
  • Indicates "REFUELING SYSTEM SERVICE REQUIRED" on the information screen in the multi-information display.
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Bypass valve failed.
  • Shorted bypass valve circuit, harness damage or connector damage.
  • ECM failed.

 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), check evaporative emission system component test item 1 and 2: Bypass Valve.
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Turn on the power supply mode of the electric motor switch.
(3) Check the following items in the evaporative emission system component test. Refer to Evaporative Emission System Component Test Reference Table .
  1. Item 1: Bypass Valve Solenoid ON
  2. Item 2: Bypass Valve Solenoid OFF
(4) Turn off the power supply mode of the electric motor switch.
Is the solenoid operating properly?
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 .
Go to Step 2.
 
STEP 2. Check of short to power supply in VAPR line between bypass valve connector and ECM connector.
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 bypass valve (integrated in evaporative emission canister).
(1) Replace the bypass valve (integrated in evaporative emission canister).
(2) Turn on the power supply mode of the electric motor switch.
(3) Check the following items in the evaporative emission system component test. Refer to Evaporative Emission System Component Test Reference Table .
  1. Item 1: Bypass Valve Solenoid ON
  2. Item 2: Bypass Valve Solenoid OFF
(4) Turn off the power supply mode of the electric motor switch.
Is the solenoid operating properly?
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 a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P1446 set?
Retry the troubleshooting.
The inspection is complete.