P0443

CIRCUIT DESCRIPTION
The Evaporative Emission (EVAP) purge valve is Pulse Width Modulated (PWM). The Powertrain Control Module (PCM) controls the EVAP purge valve duty cycle by controlling the amount of purge valve ON time. The scan tool displays the amount of ON time as a percentage.

An ignition voltage is supplied directly to the EVAP purge valve. The PCM controls the EVAP purge valve by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. The PCM monitors the status of the driver. If the PCM 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 6.0-18.0 volts.

CONDITIONS FOR SETTING THE DTC
^ The PCM 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
^ First failure:
- The MIL is not turned ON.
- A DTC is stored in memory under Failed Last Test.
- The Failure Records are stored.
^ Second consecutive drive cycle with a failure:
- The MIL is turned ON.
- A DTC is stored in memory under history.
- The Freeze Frame data is stored.
- The Failure Records are stored.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after the third consecutive trip the diagnostic has run and passed.
^ The history DTC will clear if the fault conditions have not been detected for 40 warm-up cycles.
^ A scan tool can be used to clear DTC information.

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 decrease as the commanded state is decreased. Repeat the commands as necessary.
5. This step verifies that the PCM is providing ground to the EVAP purge valve.
6. This step tests if a ground is constantly being applied to the EVAP purge valve.