DTC P0446: EVAP System Vent Control Circuit Low Input
- Turn ignition on. Using voltmeter connected to ground, backprobe ECM connector B134 (35-pin connector) terminal No. 10. See Figure. If voltage is 10 volts or less, go to next step. If voltage is more than 10 volts, check for an intermittent problem, as system has returned to normal at this time. Check for poor contact at ECM connector and drain valve connector.
- Turn ignition off. Disconnect drain valve connector and ECM connector B134 (35-pin connector). Using an ohmmeter, measure resistance between drain valve connector terminal No. 2 and ground. See Fig 1. If resistance is more than 10 ohms, go to next step. If resistance is 10 ohms or less, check for short in wiring between ECM and drain valve connectors. See appropriate wiring diagram in WIRING DIAGRAMS
article.
Courtesy of SUBARU OF AMERICA, INC.
- Measure resistance between drain valve connector terminal No. 2 and ECM connector B134 (35-pin connector) terminal No. 10. If resistance is one ohm or less, go to next step. If resistance is more than one ohm, check for an open in wiring between ECM and drain valve connectors.
- Turn ignition off. Measure resistance between drain valve terminals. If resistance is 10-100 ohms, go to next step. If resistance is less than 10 ohms or more than 100 ohms, replace drain valve.
- Turn ignition on. Using voltmeter connected to ground, measure voltage at drain valve connector terminal No. 1. If voltage is more than 10 volts, check for poor connection at drain valve connector. If voltage is 10 volts or less, check for an open in wiring between main relay and drain valve connector. If okay, check for poor contact at main relay connector.