DTC P1441 - EVAP SYSTEM FLOW DURING NON-PURGE Pontiac Firebird IV

Note. For circuit reference, see the appropriate WIRING DIAGRAMS article. For connector and terminal identification, see CONNECTOR IDENTIFICATION .

Circuit Description

EVAP vacuum switch is a normally closed switch, mounted in vacuum line between EVAP canister and EVAP solenoid. Battery voltage is supplied to switch through a pull-up resistor in PCM. When PCM commands EVAP canister purge solenoid valve open (purge on), engine vacuum draws evaporative emissions from canister and EVAP switch opens (signal voltage high) providing feedback to PCM, indicating EVAP system is operating. When PCM commands purge off, EVAP vacuum switch closes (signal voltage low), confirming that purging has ceased.

DTC will set when following conditions are present

1. DTCs P0100, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0323, P0325, P0327, P0332, P0335, P0336, P0372, P0400, P0403, P0410, P0412, P0420, P0430, P0443, P0500, P0502, P0503, P0506, P0507, P0530, P0531, P0719, P0758, P1120, P1121, P1221, P1222, P1415, P1642 or P1652 not set.
2. Engine coolant temperature less than 239°F (115°C).
3. IAT more than 37°F (3°C) on power up.
4. Engine speed 500-3000 RPM.
5. Map less than 70 kPa.
6. BARO more than 77 kPa.
7. Purge not enabled.
8. PCM detects high signal voltage on EVAP vacuum switch signal circuit when PCM is commanding purge on.
9. Conditions met for 5 seconds.