Circuit Description

Evaporative (EVAP) emissions canister purge is controlled by a solenoid valve which allows manifold vacuum to purge canister when energized (purge on) by PCM. A vacuum switch in purge line is used to detect when system is being purged. PCM supplies and reads EVAP purge vacuum switch signal. If switch is open (purge detected) when not commanded by PCM, DTC P1441 is set.

Conditions required to set DTC are:

• No ECT, IAT, VSS, MAP, EGR, EVAP, system voltage, vacuum switch or TP sensor DTCs set.
• BARO is more than 72.3 kPa.
• Start-up intake air and coolant temperature readings are 40-95°F (4.2-35°C).
• Difference between ECT and IAT at startup is less than 12.2°F (6.75°C).
• Fuel tank is between 15 percent and 85 percent.
• Fuel tank vacuum is greater than 2 in. H₂ O for 2 seconds.