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Home >> Acura >> 1995 >> 2.5TL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Trouble Codes >> Code P1508 - Idle Air Control (IAC) Valve
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Code P1508 - Idle Air Control (IAC) Valve

  1. Connect and operate scan tester, following manufacturer's instructions. Clear codes. Start engine. Retrieve codes. If Code P1508 appears, go to next step. If Code 1508 does not appear, problem is intermittent. Inspect for poor connections or loose wires associated with IAC and ECM, then repair as necessary.
  2. Turn ignition off. Unplug IAC valve connector. Turn ignition on. Measure voltage between harness connector Yellow/Black wire and ground. If battery voltage exists, go to next step. If battery voltage does not exist, repair open Yellow/Black wire between IAC valve and main relay.
  3. Turn ignition off. Reconnect wiring to IAC valve. Unplug 26-pin connector from ECM. Turn ignition on. Test for battery voltage between ECM harness connector pin A5 (Black/Blue wire) and ground. 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 and ECM.
  4. Momentarily connect ECM connector terminals A5 (Black/Blue wire) and A12 (Black wire) with jumper wire. If IAC valve clicks, temporarily substitute known good ECM, then retest system. If IAC valve does not click, temporarily substitute known good IAC valve, then retest system.
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