Circuit Description
The Evaporative Emission (EVAP) System is used to prevent fuel vapors from venting to the atmosphere. The EVAP canister purge solenoid valve is normally closed. The engine control module (ECM) controls the EVAP canister purge solenoid valve by providing ground to the EVAP canister purge solenoid valve 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 valve control circuit for low and high voltage faults. If the ECM detects that the voltage of the EVAP canister purge solenoid valve control circuit is above a predetermined threshold when the EVAP canister purge solenoid valve is commanded OFF, DTC P0459 sets.
Conditions for Running the DTC
| • | DTC P0458 is not set. |
| • | The engine speed is more than 40 RPM. |
| • | The battery voltage is more than 8.05 volts and less than 18 volts. |
| • | The vehicle is moving. |
Conditions for Setting the DTC
| • | The control circuit voltage of the EVAP canister purge solenoid valve is above 1.25 volts when the EVAP canister purge solenoid valve is commanded ON. |
| • | 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 |
Did you find and correct the condition? | Go to Step 9 | Go to Step 4 |
4 |
Did DTC P0459 fail this ignition? | Go to Step 5 | Go to Step 7 |
5 | Test the control circuit of the EVAP canister purge solenoid valve for a short to voltage. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
6 | Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
7 | Replace the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Replacement. Did you complete the replacement? | Go to Step 9 | -- |
8 | Replace the ECM. Refer to Engine Control Module Replacement. Did you complete the replacement? | Go to Step 9 | -- |
9 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 10 |
10 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
