P1441

Diagnostic Chart:

Wiring 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 P0100, P0101, P0102, P0103, P0106, P0323, P0325, P0327, P0332, P0335, P0336, P0372, P0400, P0403, P0410, P0412, P0420, P0430,P0441, P0443, P0500, P0502, P0503, P0506, P0507, P0530, P0531, P071 9, P0758, P1415, P1642, P1652 not set.

^ ECT less than 115°C (239°F)

^ IAT greater than 3°C (37°F)

^ Engine speed between 500 and 3000 RPM

^ TP Angle less than 50%

^ MAP less than 70 kPa

^ BARO greater than 77 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 present for 5 seconds

ACTION TAKEN WHEN THE DTC SETS

^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails.

^ The PCM will record operating conditions at the time the diagnostic fails. The first time the diagnostic fails, this information will be stored in Failure Records. If the diagnostic reports a failure on the second consecutive drive trip, the operating conditions at the time of failure will be written to Freeze Frame and the Failure record will be updated.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not tail.

^ A last test tailed (Current DTC) will clear when the diagnostic runs and does not tail.

^ A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

^ PCM battery voltage is interrupted.

^ Using a Scan tool.

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 intermittents, refer to Symptoms. Testing and Inspection

TEST DESCRIPTION

Number(s) below refer to 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.