P0448

Wiring Diagram:

EVAP Vent Solenoid Control Circuit High Voltage:

P0448- EVAP VENT SOLENOID CONTROL CIRCUIT HIGH VOLTAGE
The evaporative emission (EVAP) system is used to store fuel vapors as to reduce the amount of unburned fuel from escaping into the atmosphere. The EVAP vent solenoid is solely for EVAP leak diagnostics Outside air flows around the normally open valve (except during portions of the EVAP diagnostic test) through the EVAP canister to the fuel tank. This allows the fuel tank to be at atmospheric pressure, around 101 kpa. The ECM controls the solenoid by supplying it ground whenever the EVAP system is not venting (during the EVAP leak diagnostic test). When the solenoid is commanded Off (circuit not grounded), the voltage level at the ECM should be high (ignition voltage). When the solenoid is commanded On (circuit grounded), the voltage level at the ECM should be low. The ECM EVAP vent solenoid feedback circuit uses a pull-up voltage (4.6-6.6 volts), which allows the ECM to individually differentiate between an open. short to ground or short to voltage. DTC P0448 will set if the ECM detects higher than normal feedback voltage when EVAP vent solenoid is commanded On with engine running.

DTC PARAMETERS
DTC P0448 will set if EVAP vent solenoid feedback voltage is greater than 6.6 volts when EVAP vent solenoid is commanded On when:
^ Condition exists for longer than 0.5 seconds
^ Engine speed is greater than 40 rpm
^ Battery is between 7.5 and 15.0 volts

DTC P0448 diagnostic runs continuously once the above conditions have been met.

P0448 is a type B DTC

DIAGNOSTIC AIDS
To locate an intermittent problem, use Scan tool to command EVAP VENT SOLENOID On and Off with ignition On, engine Off. Wiggling wires while listening for the EVAP vent solenoid to stop clicking may locate a shorted solenoid or the area where a short to voltage in the wiring may exist.

EVAP vent solenoid resistance: 18-27 ohms