Circuit Description
The Evaporative Emission (EVAP) System is used to prevent fuel vapors from venting to the atmosphere. The EVAP canister purge solenoid is normally closed. The engine control module (ECM) controls the EVAP canister purge solenoid by providing ground to the EVAP canister purge solenoid control circuit. This allows ambient air to be drawn through the EVAP canister to the intake manifold so that the fuel vapors that were stored in the EVAP canister can be consumed by the engine. The ECM monitors the EVAP canister purge solenoid control circuit for low and high voltage faults. If the ECM detects that the voltage of the EVAP canister purge solenoid control circuit is below a predetermined threshold when the EVAP canister purge solenoid is commanded OFF, DTC P0444 sets.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The battery voltage is more than 8.05 volts and less than 18 volts. |
| • | The EVAP canister purge solenoid is commanded OFF. |
Conditions for Setting the DTC
| • | The voltage of the EVAP canister purge control circuit is below 1.25 volts. |
| • | The above condition is met for more than 0.5 seconds |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | 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 non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics , Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 |
Did the DTC fail this ignition? | Go to Step 3 | Go to Intermittent Conditions |
3 | Test for an intermittent and for a poor connection at the evaporative emission (EVAP) canister purge solenoid. 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 11 | Go to Step 4 |
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 8 |
5 |
Does the EVAP Purge -- Low Volts test pass? | Go to Step 9 | Go to Step 6 |
6 | Test the control circuit of the EVAP canister purge solenoid for an open or 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 11 | Go to Step 7 |
7 | Test for an intermittent and for a poor connection at the engine control module (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 11 | Go to Step 10 |
8 | Repair the open circuit in the ignition 1 voltage circuit of the EVAP canister purge solenoid. Did you complete the repair? | Go to Step 11 | -- |
9 | Replace the EVAP canister purge solenoid. Refer to Evaporative Emission Canister Purge Solenoid Replacement . Did you complete the replacement? | Go to Step 11 | -- |
10 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | Go to Step 11 | -- |
11 |
Did the DTC fail this ignition? | Go to Step 3 | Go to Step 12 |
12 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
