Circuit Description
The powertrain control module (PCM) supplies a ground to energize, or open,
the canister vent solenoid, allowing vacuum to purge the canister. The ground is pulse
width modulated (PWM), pulse ON and OFF several times per second, to control the flow
of purge vapors from the canister. A feedback detection circuit in the PCM monitors
the circuit for proper operation. When the solenoid is being commanded ON, the PCM
feedback should be low, and when commanded OFF, the PCM feedback should be high. If
feedback is not low or high as expected, DTC P0449 will be set.
Conditions for Setting the DTC
The PCM continually monitors the vent solenoid circuit. DTC P0449 will
set if:
| • | The solenoid is commanded ON and feedback voltage is above 3 volts. |
| • | The solenoid is commanded OFF and the feedback voltage is below 7 volts. |
Diagnostic Aids
| • | An intermittent open or short in the harness will result in a DTC P0449 |
| • | Check the tightness of the female terminal gripe with a spare male terminal.
Inspect for corrosion at the terminal locations. A corroded or loose connection at
any of the terminal locations can result in a DTC P0449. |
| • | Resistance of the EVAP vent solenoid is 15-35 ohms. |
| • | Check the 10 amp IGN fuse in the IPJB. |
