Note. For circuit reference (Схема №11)
Note. EVAP Diagnostic Station (P/N J41413 ), or similar, is necessary for accurate diagnostics of EVAP system. This tool will be necessary for vacuum and pressurized leakdown testing of EVAP systems. It is equipped with 2 additional gauges to measure vacuum in inches of mercury (in. Hg), and to measure vapor flow in inches of water (in. H2O), within an EVAP circuit.
Circuit Description
Evaporative (EVAP) emissions canister purge is controlled by a solenoid valve which allows ported vacuum to purge canister when energized (purge on) by PCM. A vacuum switch in the 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, MAF, MAP, or TP sensor DTCs set.
- BARO is more than 72.3 kPa.
- Start-up IAT and ECT are between 38-90°F (4-32°C).
- Difference between ECT and IAT is less than 12°F (7°C).
- Vehicle speed is less than 60 MPH.
- Fuel tank is between 10% and 90%.
- Fuel tank vacuum is greater than 6 in. H2O.
Diagnostic Aids
Check EVAP canister for damage or blockage. Check vacuum hoses for damage or incorrect routing. Check for restrictions in fuel vapor line, purge hose, or EVAP canister vent. Check for faulty connections or damaged harness. If connections and harness appear okay, observe EVAP VACUUM SW display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.