Circuit Description
The evaporative emission (EVAP) canister vent valve is used for EVAP system diagnostics. The EVAP canister vent valve is a normally open valve. Battery positive voltage is supplied directly to the EVAP canister vent valve. The engine control module (ECM) controls the solenoid by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. If the ECM detects the control circuit voltage is more than a predetermined value when the circuit is commanded ON, this DTC sets.
The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister vent valve.
Control Module Command | EVAP Canister Vent Valve Position |
|---|---|
ON | CLOSED |
OFF | OPEN |
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0499 Evaporative Emission (EVAP) Vent Solenoid Control Circuit High Voltage
Conditions for Running the DTC
| • | Before the ECM can report DTC P0499 failed, DTC P0451 must run and pass. |
| • | DTC P0455 must run before the ECM enables the EVAP canister vent valve. |
| • | The engine speed is more than 80 RPM. |
| • | The ignition 1 voltage is between 10.5-18 volts. |
| • | The ECM has commanded the EVAP canister vent valve ON and OFF at least once during the ignition cycle. |
| • | DTC P0499 runs continuously once the above conditions have been met. |
Conditions for Setting the DTC
| • | The ECM detects the voltage on the EVAP canister vent valve control circuit is more than 4.6 volts when the driver is commanded ON. |
| • | The condition is present for more than 4 seconds. |
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 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
| • | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. |
| • | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views . |
| • | If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault if there is a condition with the circuit or a connection. The output driver module (ODM) information is in the ODM data list. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Test Description
The number below refers to the step number on the diagnostic table.
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 - Vehicle? | Go to Step 2 | |
Does the evaporative emission (EVAP) canister vent valve turn ON and OFF? | Go to Step 3 | Go to Step 4 | |
3 |
Did the DTC fail this ignition? | Go to Step 4 | Go to Diagnostic Aids |
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 6 |
5 |
Important: The control circuit for the solenoid is pulled up to voltage within the engine control module (ECM), 2.6-4.6 volts on the control circuit is normal. Test the control circuit of the EVAP canister vent valve for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 10 | Go to Step 7 |
6 | Test for shorted terminals and for poor connections at the EVAP canister vent valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 10 | Go to Step 8 |
7 | Test for shorted terminals and for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 10 | Go to Step 9 |
8 | Replace the EVAP canister vent valve. Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement . Did you complete the replacement? | Go to Step 10 | -- |
9 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 10 | -- |
10 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 11 |
11 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
