DTC 25: Idle Air Control (IAC)

Check Power Supply

Turn ignition off. Disconnect IAC valve wiring harness connector. Measure voltage between harness connector terminal "A" and ground. See Fig 1 and Fig 2 . If battery voltage is present, go to next step. If battery voltage is not present, repair Black/Red wire continuity between ignition coil and ignition switch.

Check Output Signal Circuit

Turn ignition off. Disconnect ECM harness connector. Verify harness continuity between ECM terminal No. 103 and IAC valve connector terminal "B". See Fig 3 . If continuity is present, go to next step. If continuity is not present, repair harness or connectors as necessary.

Check Component

Disconnect IAC valve wiring harness connector. Measure resistance across connector terminals. If about 10 ohms are not present, service IAC valve plunger and spring. If about 10 ohms are present, IAC valve is okay. Check ECM connector terminals for corrosion or damage. Repair as necessary and perform FINAL CHECK.

Fig 1: Locating IAC Harness Connector (G20)

G95C31874

Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 2: DTC 21, Checking Power Supply (G20)

G95D31875

Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 3: DTC 21, Checking Output Signal Circuit (G20)

G95E31876

Courtesy of NISSAN MOTOR CO., U.S.A.