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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 40 (Engine Controls - Self-Diagnostics - 2.5) >> Diagnostic Tests >> DTC P1448: EVAP Canister Vent Control Valve >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check hose connected to EVAP-CVCV for damage and blockage. See Figure. If problem exists, repair as necessary and retest system. If problem does not exist, go to next step.
  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.
    CAUTION: DO NOT apply more than 5.91 in. Hg of vacuum to EVAP-CSPS. Replace EVAP-CSPS if it has been dropped from a height of more than 20" (.5 m) onto a hard surface such as concrete.
    10. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  10. Remove EVAP-CSPS with its harness connector connected. Turn ignition on. Using a hand vacuum pump, apply 2.76 in. Hg of vacuum to EVAP-CSPS. Measure voltage between ground and ECM terminal No. 84 (Pink wire) by backprobing. See Figure and Figure . Voltage should be .4-.6 volt. Disconnect vacuum pump. Voltage should be 3.0-3.6 volts. If voltage is as specified, go to next step. If voltage is not as specified, replace EVAP-CSPS and retest system.
  11. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLESHOOTING - 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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