P0443

CIRCUIT DESCRIPTION
An ignition voltage is supplied directly to the evaporative emission (EVAP) canister purge valve. The EVAP canister purge valve is pulse width modulated (PWM). The scan tool displays the amount of ON time as a percentage. The control module monitors the status of the driver. The control module controls the EVAP canister purge valve ON time by grounding the control circuit via an internal switch called a driver. If the control module detects 3.5 volts on the control circuit while the driver is commanded OFF, this DTC sets.

CONDITIONS FOR RUNNING THE DTC
- The engine speed is more than 400 RPM.
- The system voltage is between 8-18 volts.

CONDITIONS FOR SETTING THE DTC
- The control module detects 3.5 volts on the EVAP purge valve control circuit with the driver commanded OFF.
- The fault is present for 50 seconds, cumulative during the drive cycle.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

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 clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

TEST DESCRIPTION

Step 1-4:

Steps 5-10:

Steps 11-13:

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.
4. This step tests for proper ignition voltage supply to the EVAP purge valve.
5. This step tests the control modules ability to supply a ground to the EVAP purge valve.