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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: DO NOT disassemble water separator.
  1. Turn ignition off. Remove water separator located on charcoal canister. Inspect water separator for cracks or blockage. With water separator port "A" plugged, blow air into port "B". See Figure. Air should flow out of port "C". With port "C" plugged, blow air into port "B". Air should flow out of port "A". If operation is as specified, go to next step. If operation is not as specified, replace water separator and retest system.
  2. Remove EVAP-CVCV. Check EVAP-CVCV for rust and damage. Rust should not exist in port "B". See Figure. If problem exists, replace EVAP-CVCV and retest system. If problem does not exist, go to next step.
  3. Using fused jumper wires, apply battery voltage between EVAP-CVCV terminals (component side). See Figure. Air applied to port "A" should not flow from port "B". Remove jumper wires. Air applied to port "A" should now flow from port "B". If EVAP-CVCV operates as specified, go to step  5. If EVAP-CVCV does not operate as specified, go to next step.
  4. Clean EVAP-CVCV ports with compressed air. Repeat step  3. If EVAP-CVCV now operates as specified, go to next step. If EVAP-CVCV still does not operate as specified, replace EVAP-CVCV and retest system.
  5. Remove vacuum cut valve. See Figure. Plug ports "C" and "D". See Fig 1. Apply vacuum to port "A". Vacuum should not exist at port "B". Apply vacuum to port "B". Vacuum should exist at port "A". Blow air in port "B". Air should flow out of port "A" with some resistance. Unplug ports "C" and "D". Blow air in port "A". Air should flow freely out of port "C". Blow air in port "B". Air should flow freely out of port "D". If operation is as specified, go to next step. If operation is not as specified, replace vacuum cut valve and retest system.
  6. Remove EVAP canister with EVAP-CVCV attached. Turn EVAP canister so EVAP-CVCV is pointing down. If water drains out, go to next step. If water does not drain out, go to step  8.
  7. Weigh EVAP canister with EVAP-CVCV attached. Weight should be less than 4 lbs. (1.8 kg). If weight is as specified, go to next step. If weight is not as specified, check EVAP canister for damage. Also, check hose between EVAP canister and water separator for clogging or poor connection. Repair hose or replace EVAP canister as necessary and retest system.
  8. Check hose connected to EVAP-CSPS for damage, blockage and improper routing. See VACUUM DIAGRAMS article. Repair or replace hose as necessary and retest system. If hose is okay, go to next step.
  9. Disconnect EVAP-CSPS harness connector. Inspect connector for water. If water exists, replace EVAP-CSPS and retest system. If water does not exist, go to next step.
  10. Check EVAP-CSPS function. Perform DTC CONFIRMATION TEST  under DTC P0450: EVAP CONTROL SYSTEM PRESSURE SENSOR. If first trip DTC is detected, replace EVAP-CSPS and retest system. If first trip DTC is not detected, go to next step.
  11. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Testing Vacuum Cut Valve & Vacuum Cut Valve By-Pass Valve
G99G08867Courtesy of NISSAN MOTOR CO., U.S.A.
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