P0498

DTC P0498

CIRCUIT DESCRIPTION




This diagnostic monitors the evaporative emission (EVAP) system for faults in the EVAP vent solenoid electrical circuit. Battery positive voltage is supplied directly to the EVAP canister vent valve. The control module grounds the EVAP canister vent valve control circuit to close the valve by means of an internal switch called a driver. The scan tool displays the commanded state of the EVAP canister vent valve as ON or OFF. The control module monitors the status of the driver. If the control module detects low voltage on the control circuit when the driver is commanded OFF, this DTC sets.




The table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states, of the EVAP canister vent valve.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0498 Evaporative Emission (EVAP) Vent Solenoid Control Circuit Low Voltage.

CONDITIONS FOR RUNNING THE DTC
- The battery voltage is 10.1 volts.
- The engine is running.
- DTC P0498 runs continuously once the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The control module detects low voltage on the control circuit when the driver is commanded OFF.

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 3 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.

TEST DESCRIPTION

Steps 1-11:

Steps 12-13:

The numbers below refer to the step numbers on the diagnostic table.
1. The Diagnostic System Check - Vehicle prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool, if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
11. After replacing the PCM, a new minimum throttle position and idle speed must also be established.