P1441
Electrical Diagram:
CIRCUIT DESCRIPTION
The EVAP vacuum switch is a normally closed switch connected to ground, mounted in the vacuum line between the EVAP canister and the EVAP solenoid. 12 volts is supplied to the switch through a pull-up resistor in the PCM. When the PCM commands the EVAP canister purge solenoid valve open (purge ON) and engine vacuum draws the evaporative emissions from the canister, the EVAP vacuum switch opens (signal voltage high) providing feedback to the PCM that the EVAP system is operating. When the PCM commands purge OFF, the EVAP vacuum switch closes (signal voltage low) confirming purging has ceased.
CONDITIONS FOR SETTING THE DTC
^ DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0441, P0443, P1120, P1121, P1220, P1221 not set.
^ ECT is less than 115°C (239°F).
^ IAT is greater than 3°C (37°F) at power up.
^ IAT is less than 80°C (176°F).
^ The difference between ECT and IAT is less than 10°C (50°F) at power up.
^ Engine speed is between 500 and 2500 RPM.
^ TP Angle is between 10% and 60%.
^ MAP is between 20 kPa and 80 kPa.
^ BARO is greater than 75 kPa.
^ Purge not enabled.
^ The PCM detects high signal voltage on the EVAP vacuum switch signal circuit when the PCM is not commanding purge ON.
^ Fault is present for 5 seconds.
ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp on the second consecutive drive trip that the diagnostic runs and fails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive drive trip, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure records.
CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
^ A last test failed (current DTC) clears when the diagnostic runs and does not fail.
^ A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
^ The PCM battery voltage is interrupted.
^ Use a scan tool in order to clear the MIL/DTC.
DIAGNOSTIC AIDS
Before replacing any components, visually/physically check for the following:
^ Mis-routed harness.
^ Rubbed through wire insulation
^ Broken wire inside the insulation
^ Kinked or damaged vacuum hoses
^ Physically damaged system components
^ Inspect components and vacuum lines for traces of carbon or other contaminants. The presence of foreign material may be causing a restriction in the system or preventing the solenoid valve from closing properly. Either condition may cause a DTC to set.
For an intermittent condition, refer to Symptoms. Testing and Inspection
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
5. Since the vacuum switch only requires a vacuum of only a few inches of water to operate (a very small unit of vacuum), a properly operating switch will transition even with the canister end of the hose disconnected and un-plugged.