Circuit Description
The evaporative emission (EVAP) system includes the following components:
| • | Fuel tank |
| • | EVAP vent solenoid |
| • | Fuel tank pressure sensor |
| • | Fuel pipes and hoses |
| • | Fuel vapor lines |
| • | Fuel cap |
| • | EVAP canister |
| • | Purge lines |
| • | EVAP emission canister purge valve |
| • | EVAP service port |
The EVAP purge canister solenoid is controlled by the engine control module (ECM). The ECM applies a ground to the EVAP purge canister solenoid. The ECM determines when to activate the EVAP canister purge solenoid depending on operating conditions, including throttle position (TP), engine speed, engine coolant temperature (ECT), and ambient temperature.
The diagnostic trouble code (DTC) will detect an open or short circuit.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0443 Evaporative Emissions (EVAP) Purge Solenoid Control Circuit
Conditions for Running the DTC
| • | The ignition is ON. |
| • | DTC P0606 is not set. |
| • | The ignition 1 voltage is more than 11 volts. |
| • | DTC P0443 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match, for more than 4 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the third 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 4 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. |
Diagnostic Aids
Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and the Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same Freeze Frame conditions, such as RPM, load, vehicle speed, temperature, etc., that were noted. This will isolate when the DTC failed.
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). When the purge valve is commanded to 50 percent, you should hear or feel a clicking. The clicking 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. The rate should decrease when the commanded state is decreased. Repeat the commands as necessary.
-
This step tests if a ground is constantly being applied to the EVAP purge valve.
-
This step verifies that the ECM is providing ground to the EVAP purge valve.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views | |||
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 the valve is commanded to 50 percent? | Go to Step 3 | Go to Step 4 | |
3 |
Did 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 |
Is the test lamp Illuminated? | Go to Step 8 | Go to Step 6 | |
With a scan tool command the EVAP purge valve to 50 percent. Does the test lamp illuminate when the EVAP purge valve is commanded to 50 percent? | Go to Step 9 | Go to Step 7 | |
7 | Test the control circuit of the EVAP purge valve for an open or for a 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 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 ECM. 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 1 voltage circuit of the EVAP purge valve. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 14 | -- |
12 | Replace the EVAP purge valve. Did you complete the replacement? | Go to Step 14 | -- |
13 | Replace the control module. Refer to Engine Control Module Replacement . Did you complete the replacement? | Go to Step 14 | -- |
14 |
Did the DTC fail this ignition? | Go to Step 15 | Go to Step 2 |
15 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK | |
