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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 111 (Engine Controls - Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0446: EVAP Vent System Performance >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition on, engine off. Remove fuel cap. Using scan tool, monitor FUEL TANK PRESS. SENSOR. If voltage is 1.3-1.6 volts, go to step  3 . If voltage is not 1.3-1.6 volts, go to next step.
  2. If voltage is less than 0.1 volt, see DTC P0452: EVAP FUEL TANK PRESSURE SENSOR CIRCUIT - LOW VOLTAGE  . If voltage is 0.1-1.3 volts or 1.6-4.9 volts, replace fuel tank pressure senor. If voltage is more than 4.9 volts, see DTC P0453: EVAP FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE  .
  3. Install fuel cap. Start engine. Using scan tool, perform EVAP SYSTEM PERF special function by commanding a 10 percent duty cycle to the EVAP purge solenoid. Using scan tool, monitor FUEL TANK PRESS. SENSOR while holding engine speed to 3000 RPM. Wait for fuel tank pressure to reach 3.5 volts or more, then using scan tool, command EVAP purge solenoid off by pressing EXIT. If fuel tank pressure returns to 1.3-1.6 volts within 5 seconds, problem is intermittent. See DIAGNOSTIC AIDS  . If fuel tank pressure does not return to 1.3-1.6 volts, go to next step.
  4. Turn ignition ON, engine OFF. Raise vehicle. Remove right rear wheel well. Using scan tool, command EVAP VENT SOLENOID to 20 percent duty cycle and listen for solenoid to click at charcoal canister in front of fuel tank. If solenoid clicks, EVAP vent system is blocked. Check for EVAP vent solenoid filter clogged, blocked EVAP canister or kinked/pinched EVAP lines/hoses. If solenoid does not click, go to next step.
  5. Check EMISS fuse (10-amp). Replace and retest if open. If fuse continues to open, check for short to ground in White wire. Check main relay. Power to EMISS fuse is supplied through main relay. Disconnect EVAP vent solenoid. Connect Noid Light (SA9194E) between EVAP vent solenoid connector terminals. Using scan tool, command EVAP VENT SOL on. If test light illuminates, check EVAP vent solenoid connector. If connector is okay, replace EVAP vent solenoid. If test light does not illuminate, go to next step.
  6. Connect test light between EVAP vent solenoid connector terminal "A" (White wire) and ground. If test light is illuminates, go to next step. If test light does not illuminate, repair open in White wire between EVAP vent solenoid and underhood fuse block.
  7. Turn ignition off. Disconnect ECM connector J2. Check for continuity between EVAP vent valve connector terminal "B" (White wire) and ground. If continuity exists, repair short to ground in White wire between EVAP vent solenoid and ECM. If continuity does not exist, check White wire for open between EVAP vent solenoid and ECM. If wire is okay, replace ECM.
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