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DTC P1508 - IDLE AIR CONTROL (IAC) VALVE Honda Prelude V

Testing & Diagnostics ~241 words
  1. Perform PCM reset procedure. See «TESTS W/CODES - INTRODUCTION»(ref-16345) article. Start engine and warm to normal operating temperature. If DTC P1508 is indicated, go to next step. If DTC P1508 is not indicated, problem is intermittent. System is okay at this time. Check for poor connections or loose wires between IAC valve connector and PCM connector. See «WIRING DIAGRAMS»(ref-16355) article.
  2. Turn ignition off. Disconnect IAC valve 2-pin connector. Turn ignition on. Measure voltage between ground and IAC valve connector terminal No. 2 (Yellow/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Yellow/Black wire between IAC valve connector and PGM-FI main relay. See «WIRING DIAGRAMS»(ref-16355) article.
  3. Turn ignition off and reconnect IAC valve 2-pin connector. Disconnect PCM 32-pin connector "A". Turn ignition on. Using backprobe set, measure voltage between ground and PCM 32-pin connector "A" terminal A12 (Black/Blue wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short in Black/Blue wire between IAC valve connector and PCM 32-pin connector "A". See «WIRING DIAGRAMS»(ref-16355) article.
  4. Momentarily connect a fused jumper wire between PCM 32-pin connector terminal A10 (Black wire) and terminal A12 (Black/Blue wire), several times. (Схема №1) If IAC valve does not click, replace IAC valve. If IAC valve clicks, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM.

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