SC 400 V8-4.0L (1UZ-FE) (1997)
Idle Air Control Valve: Component Tests and General Diagnostics
Component Inspection
IAC VALVE INSPECTION
1. INSPECT VALVE RESISTANCE
NOTICE: "Cold" and "Hot" in these sentences express the temperature of the coils themselves. Cold is from 100°C (14°F) to 50°C (122°F) and
Hot is from 60°C (122°F) to 100°C (212°F).
Using an ohmmeter, measure the resistance between the terminals (B1 - S1 and S3, B2 - S2 and S4).
Resistance:
Cold: 31 - 61 Ohms
Hot: 38 - 71 Ohms
If resistance is not as specified, replace the IAC valve.
2. INSPECT IAC VALVE OPERATION
(a) Apply battery voltage to terminal B1 and B2 and while repeatedly grounding S1 - S2 - S3 - S4 - S1 in sequence, check that the valve moves
toward the closed position.
(b) Apply battery voltage to terminal B1 and B2 and while repeatedly grounding S4 - S3 - S2 - S1 - S4 in sequence, check that the valve moves
toward the open position.
If operation is not as specified, replace the IAC valve.
On-Vehicle
IDLE AIR CONTROL (IAC) VALVE ON-VEHICLE INSPECTION
INSPECT IAC VALVE FOR OPERATING SOUND
Check that there is a clicking sound immediately after stopping the engine.
If the rpm operation is not as specified, check IAC valve, wiring and ECM.