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Home >> Isuzu >> 2002 >> Trooper S, 4WD, Part Time >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Emission Systems & Sub-Systems >> EVAP Canister Purge Valve Solenoid Check >> Diagnostic Procedure

Diagnostic Procedure

  1. At throttle body disconnect vacuum hose that goes to EVAP purge valve solenoid. Turn ignition on. Using a hand-held vacuum pump, apply 10 in. Hg (34 kPa) to EVAP purge valve solenoid. If valve holds vacuum, go to step  3. If valve does not hold vacuum, leave ignition on and go to next step.
  2. Disconnect EVAP purge valve solenoid harness connector. Using a hand-held vacuum pump, apply 10 in. Hg (34 kPa) to EVAP purge valve solenoid. If valve holds vacuum, go to step  4. If valve does not hold vacuum, go to step  7.
  3. At throttle body plug disconnected vacuum port. Connect Tech 2 or equivalent scan tool to Data Link Connector (DLC). DLC is located under small cover on lower left side of instrument panel. On scan tool select MISCELLANEOUS TESTS and then EVAP test. Using a hand-held vacuum pump, apply 10 in. Hg (34 kPa) to EVAP purge valve solenoid. Start engine and run at 2500 RPM. Using scan tool, command EVAP purge valve solenoid On. If vacuum dropped when valve commanded on, go to step  8. If vacuum did not drop when valve was commanded on, go to step  9.
  4. Check for open or short to ground in Red/Blue wire (purge valve control signal) between purge valve and PCM. See WIRING DIAGRAMS article. If problem is found, go to next step. If no problem is found, go to step  6.
  5. Repair open or short to ground in Red/Blue wire (purge valve control signal) between purge valve and PCM. After repair, retest system.
  6. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE REPLACEMENT under POWERTRAIN CONTROL MODULE in appropriate SELF-DIAGNOSTICS article. After repair, repeat OBD-II system check. See ON-BOARD DIAGNOSTIC II SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.
  7. Replace EVAP purge valve solenoid. After repair, retest system.
  8. Turn ignition off. At throttle body, install vacuum gauge at vacuum port. Start engine and run at 2500 RPM. Momentarily snap throttle open, allowing engine to return to idle. If vacuum maintains at least 10 in Hg. (34 kPa), testing is complete. If vacuum is not maintained, check for intermittent problem. See DIAGNOSTIC AIDS .
  9. Turn ignition off. Disconnect EVAP purge valve solenoid 2-pin harness connector. Connect test light between the harness connector terminals. Turn ignition on. If test light illuminates, go to step  7. If test light does not illuminate, go to next step.
  10. Using test light connected to ground, probe EVAP purge valve solenoid harness connector terminals one at a time. If test light illuminates at both terminals, go to next step. If test light does not illuminate at both terminals, go to step  12.
  11. Repair short to voltage in Red/Blue wire (purge valve control signal) between purge valve and PCM. After repair, retest system.
  12. If test light illuminated on EVAP purge valve solenoid harness connector terminal No. 2 (Black/Yellow wire), go to next step. If test light did not illuminate on EVAP purge valve solenoid harness connector terminal No. 2, go to step  14.
  13. Check for open in Red/Blue wire (purge valve control signal) between purge valve and PCM. If problem is found, go to step  15. If no problem is found, go to step  6.
  14. Repair open in Black/Yellow wire (purge valve ignition signal) between fuse box and EVAP purge valve solenoid. After repair, retest system.
  15. Repair open in Red/Blue wire (purge valve control signal) between purge valve and PCM. After repair, retest system.
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