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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 219 (Engine Control System - System & Component Testing) >> Emission Systems & Subsystems >> Evaporative Emission Control System Diagnosis >> EVAP Canister Vent Valve Inspection

EVAP Canister Vent Valve Inspection

WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
WARNING: Do not breathe the air through the EVAP component tubes or hoses. The fuel vapors inside the EVAP components may cause personal injury.
  1. Disconnect the EVAP vent solenoid harness connector.
  2. Using DMM, measure the solenoid resistance value. See Fig 1 . The resistance should be between 25-30 ohms at 68°F (20°C).
  3. Replace the solenoid if the resistance is not within specification.
  4. Using DMM, check for continuity between each solenoid terminal and solenoid housing. See Fig 2 . The DMM should read infinite (OL).
  5. Replace the EVAP vent solenoid valve if the resistance is not within specification. A shorted valve will cause damage to the PCM.
  6. Blow air through the upper port of the EVAP vent valve. Air has to flow freely through the lower port. See Fig 3 .
  7. Replace the valve if the air does not flow through the upper port.
  8. Apply battery voltage across the solenoid terminals. See Fig 4 .
  9. Blow air through the upper port of the solenoid. Air should NOT flow through the valve. See Fig 4 .
  10. Replace the solenoid if the solenoid fails any of the tests.
Fig 1: Measuring EVAP Vent Solenoid Resistance
G00180603Courtesy of GENERAL MOTORS CORP.
Fig 2: Checking Canister Vent Valve For Internal Short
G00180604Courtesy of GENERAL MOTORS CORP.
Fig 3: Verifying Free Flow Through Lower Port
G00180605Courtesy of GENERAL MOTORS CORP.
Fig 4: Testing EVAP Canister Vent Valve Operation
G00180606Courtesy of GENERAL MOTORS CORP.