DTC P1508 (B16A2, D16Y8 M/T): Idle Air Control (IAC) Valve
WARNING: This page is about a different car, the 2000 Honda Civic. However, it is still accessible from the selected car via links, so may be relevant.
- Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING DTCS in SELF-DIAGNOSTICS - INTRODUCTION 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 at Idle Air Control (IAC) valve and PCM connectors. See appropriate wiring diagram in WIRING DIAGRAMS article.
- Turn ignition off. Disconnect IAC valve 2-pin connector. Turn ignition on. Measure voltage between ground and IAC valve harness connector terminal No. 2 (Yellow/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, check for open in Yellow/Black wire between IAC valve connector and PGM-FI main relay. See appropriate wiring diagram in WIRING DIAGRAMS article.
- Turn ignition off and reconnect IAC valve 2-pin connector. Disconnect PCM 25-pin connector "B". Turn ignition on. Measure voltage between ground and PCM 25-pin harness connector "B" terminal No. 12 (Black/Blue wire). See Figure. If battery voltage exists, go to next step. If battery voltage does not exist, check for open or short in Black/Blue wire between IAC valve connector and PCM 25-pin harness connector "B". See appropriate wiring diagram in WIRING DIAGRAMS article.
- Using a fused jumper wire, momentarily connect PCM 25-pin harness connector "B" terminals No. 2 (Black wire) and No. 23 (Black/Blue wire), several times. See Figure. 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.