P0443

CIRCUIT DESCRIPTION
An ignition voltage is supplied directly to the evaporative emission (EVAP) purge valve. The EVAP purge valve is pulse width modulated (PWM). The control module controls the EVAP purge valve ON time by grounding the control circuit via an internal switch called a driver. The scan tool displays the amount of ON time as a percentage. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, DTC P0443 sets.

CONDITIONS FOR RUNNING THE DTC
^ The engine speed is more than 400 RPM.
^ The system voltage is between 6-18 volts.

CONDITIONS FOR SETTING THE DTC
^ The control module detects that the commanded state of the driver and the actual state of the control circuit do not match.
^ The above conditions are present for a minimum of 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
The control module will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test ran and failed.

The control module will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. ^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC will clear after 40 consecutive warm-up cycles without a malfunction.
^ Use a scan tool in order to clear the MIL and the DTC.

TEST DESCRIPTION

Steps 1-4:

Steps 5-15:

The numbers below refer to the step numbers on the diagnostic table.
2. This step tests if the concern is active. The EVAP purge valve is pulse width modulated (PWM). An audible clicking should be heard when the purge valve is commanded to 50 percent and should stop when the EVAP purge valve is commanded to 0 percent. The rate at which the valve cycles should increase as the commanded state is increased and decreased as the commanded state is decreased. Repeat the commands as necessary.
5. This step tests if a ground is constantly being applied to the EVAP purge valve.
6. This step verifies that the control module is providing ground to the EVAP purge valve.