DTC P1505: Idle Air Control (IAC) Valve Opening Coil Signal Low, Or DTC P1506: Idle Air Control (IAC) Valve Opening Coil Signal High: Procedure
- Turn ignition off. Disconnect IAC valve 3-pin connector. Turn ignition on. Measure voltage between ground and IAC valve harness connector terminal No. 2 (Red/Yellow wire). See Figure . If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Red/Yellow wire between IAC valve connector and INJ fuse (10-amp), located in engine compartment fuse/relay box.
- Turn ignition off. Disconnect ECM 88-pin connector. Measure resistance of White/Green wire between IAC valve harness connector terminal No. 3 and ECM harness connector terminal No. 29. See Figure and Figure . If code is DTC P1505 and resistance is less than one ohm, go to next step. If code is DTC P1506 and resistance is less than one ohm, go to step 4 . If resistance is not as specified, repair open in White/Green wire between IAC valve and ECM.
- Check for continuity between ground and ECM harness connector terminal No. 29 (White/Green wire). If continuity does not exist, go to step 5 . If continuity exists, repair short to ground in White/Green wire between IAC valve and ECM.
- Turn ignition on. Check for voltage between ground and ECM harness connector terminal No. 29 (White/Green wire). If voltage does not exist, go to next step. If voltage exists, repair short to power in White/Green wire between IAC valve and ECM.
- Turn ignition off. Measure resistance between IAC valve harness connector terminals No. 1 and 2 (White/Yellow wire and Red/Yellow wire - component side). Also, measure resistance between IAC valve harness connector terminals No. 2 and 3 (Red/Yellow wire and White/Green wire - component side). Resistance should be 16.5-18.5 ohms at 68°F (20°C). If resistance is not as specified, replace IAC valve. If resistance is as specified, check connectors for loose, damaged or corroded terminals. If problem exists, repair connector as necessary.