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 powertrain control module (PCM) 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 PCM monitors the status of the driver. If the PCM detects an incorrect voltage for the commanded state of the driver, diagnostic trouble code (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 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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests if the concern is active. The EVAP purge valve is pulse width modulated (PWM). Clicking should be heard or felt 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.
-
This step verifies that the PCM is providing ground to the EVAP purge valve.
-
This step tests if a ground is constantly being applied to the EVAP purge valve.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
Do you hear or feel a clicking from the EVAP purge valve when it is commanded to 50 percent? | Go to Step 3 | Go to Step 4 | |
3 |
Does the DTC fail this ignition? | Go to Step 4 | Go to Intermittent Conditions |
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 11 |
Does the test lamp illuminate or pulse when the EVAP purge valve is commanded to 50 percent? | Go to Step 9 | Go to Step 6 | |
Does the test lamp remain illuminated with each command? | Go to Step 8 | Go to Step 7 | |
7 | Test the control circuit of the EVAP purge valve for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 10 |
8 | Test the control circuit of the EVAP purge valve for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
9 | Inspect for poor connections at the harness connector of the EVAP purge valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 12 |
10 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
11 | Repair the ignition voltage circuit of the EVAP purge valve for an open or short to ground. Replace the fuse if necessary. Refer to Troubleshooting with a Test Lamp and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 14 | -- |
12 | Replace the EVAP purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Did you complete the replacement? | Go to Step 14 | -- |
13 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | Go to Step 14 | -- |
14 |
Does the DTC run and pass? | Go to Step 15 | Go to Step 2 |
15 | Use a scan tool in order to observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK | |
