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Home >> Acura >> 1996 >> 3.2TL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Air Induction Systems >> Intake Air By-Pass (IAB) System >> IAB System Inspection
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IAB System Inspection

  1. IAB control solenoid valves are located at right front of engine compartment. Check IAB valve shaft for binding, sticking and smooth movement. If necessary, clean linkage and shafts with carburetor cleaner.
  2. Start engine and let idle. Remove vacuum hose from IAB low control diaphragm. See Fig 1 . Connect vacuum gauge to hose. If vacuum is not present, go to step 6). If vacuum is present, go to next step.
    Fig 1: Identifying IAB Control System
    G93G78366
  3. With engine idling, disconnect vacuum hose from IAB high control diaphragm. Connect vacuum gauge to hose. If vacuum is present, go to next step. If vacuum is not present, go to step 10).
  4. Increase engine speed to 3400 RPM. Check for vacuum at low control diaphragm hose. If vacuum is not present, go to next step. If vacuum is present, go to step 14).
  5. Increase engine speed to 4300 RPM. Check for vacuum at high control diaphragm hose. If vacuum is not present, system is okay. If vacuum is present, go to step 16).
  6. Remove vacuum hose at IAB low control solenoid. Connect vacuum gauge to hose. With engine at idle, if vacuum is present, go to next step. If vacuum is not present, check vacuum lines between solenoid, vacuum tank and intake manifold. See Fig 1 . Repair as necessary and recheck.
  7. Turn ignition off. Unplug connector from IAB low control solenoid. Turn ignition on. Measure voltage between Black/Yellow (positive) and Red/Blue (negative) wires at IAB low control solenoid connector. If battery voltage is present, replace IAB low control solenoid valve. If voltage is not present, go to next step.
  8. Measure voltage between Black/Yellow wire terminal and body ground. If battery voltage is not present, repair open in Black/Yellow wire between solenoid harness connector and fuse No. 4. If battery voltage is present, go to next step.
  9. Turn ignition off. Check for continuity between PCM terminal A22 and IAB control solenoid connector. If continuity does not exist, repair open in Yellow wire. If continuity exists, substitute a known-good PCM and retest. If symptom goes away, replace PCM.
  10. Remove vacuum hose at IAB high control solenoid. Connect vacuum gauge to hose. With engine at idle, if vacuum is present, go to next step. If vacuum is not present, check vacuum line between solenoid and intake manifold. Repair as necessary and recheck.
  11. Turn ignition off. Unplug connector from IAB high control solenoid. With engine at idle, measure voltage between Black/Yellow (positive) and Yellow (negative) wire terminals at IAB control solenoid harness connector. If battery voltage is present, replace IAB high control solenoid valve. If voltage is not present, go to next step.
  12. Measure voltage between Black/Yellow wire terminal at IAB control solenoid harness connector and body ground. If battery voltage is not present, repair open in Black/Yellow wire between IAB solenoid connector and fuse No. 4. If battery voltage is present, go to next step.
    NOTE: When substituting a known-good PCM, immobilizer code must be rewritten using Honda PGM tester, or engine will not start.
  13. Turn ignition off. Check Yellow wire for continuity between PCM terminal A22 and ground. If continuity does not exist, repair open in Yellow wire. If continuity exists, substitute a known-good PCM and retest. If symptom goes away, replace PCM.
  14. Unplug connector from IAB low control solenoid. With engine running at 3400 RPM, if vacuum is present, replace IAB low control solenoid valve. If vacuum is not present, go to next step.
  15. Turn ignition off. Unplug connector "A" from PCM. See Figure . Check continuity between ground and PCM terminal A20 (Red/Blue wire). If continuity exists, repair as necessary. If continuity does not exist, substitute a known-good PCM and retest. If symptom goes away, replace PCM.
  16. Unplug connector from by-pass high control solenoid valve. With engine running at 4000 RPM, if vacuum is present, replace by-pass high control solenoid valve. If vacuum is not present, go to next step.
  17. Turn ignition off. Unplug connector "A" from PCM. See Figure . Check continuity between PCM terminal A22 and ground. If continuity exists repair yellow wire for short to ground. If continuity does not exist, substitute a known-good PCM and retest. If symptom goes away, replace PCM.
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