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IAB Control System Check

  1. Start engine and allow to idle. Remove vacuum hose (No. 13) from IAB control diaphragm. See Fig 1 . Connect vacuum gauge to disconnected hose. If vacuum exists, go to step 6). If vacuum does not exist, remove vacuum hose (No. 12) from IAB vacuum tank. Check for vacuum. If vacuum exists, go to next step. If vacuum does not exist, repair blockage or vacuum leak between IAB vacuum tank and intake manifold then retest system.
  2. Disconnect IAB control solenoid valve 2-pin connector. Measure voltage between IAB solenoid harness connector terminals. If battery voltage is present, replace IAB control solenoid valve. If battery voltage is not present, measure voltage between ground and IAB solenoid valve harness connector Black/Yellow wire.
  3. If battery voltage is not present, repair open in Black/Yellow wire between IAB solenoid valve connector and fuse No. 14 (ECU CRUISE CONTROL) located in underdash fuse/relay box. See WIRING DIAGRAMS  section.
  4. Turn ignition off and reconnect IAB control solenoid connector. Turn ignition on. Use jumper wire to connect PCM 32-pin harness connector Black/Red (terminal A9) and Pink (terminal A26) wires. See Figure .
  5. If IAB solenoid does not click, repair open in Pink wire between IAB control solenoid valve and PCM. See WIRING DIAGRAMS  section. If IAB solenoid clicks, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM.
  6. Increase engine speed to more than 5000 RPM. Check for vacuum at hose No. 13. If vacuum does not exist, solenoid is okay. If vacuum exists, disconnect IAB control solenoid harness connector. Check for vacuum again. If vacuum still exists, replace IAB control solenoid valve. If vacuum no longer exists, turn ignition off. Disconnect PCM connector "A". See Figure .
  7. Check for continuity between ground and IAB control solenoid harness connector Pink wire. If continuity exists, repair short in Pink/Blue or Pink wire between IAB control solenoid harness connector and PCM. See WIRING DIAGRAMS  section. If continuity does not exist, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM.
    Fig 1: By-Pass Control System Component ID
    G96G09616Courtesy of AMERICAN HONDA MOTOR CO., INC.
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