Idle Speed Control (ISC) Valve
- Start engine. Idle engine for approximately 2 minutes. Turn engine off. Ensure a "clicking" sound is heard from ISC immediately after stopping engine.
- Disconnect ISC valve connector. Using a DVOM, check resistance between terminals specified in ISC VALVE RESISTANCE table. See Fig 1. If resistance is not as specified, replace ISC valve.ISC VALVE RESISTANCE
Terminals Ohms B1 & S1 Or S3 10-30 B2 & S2 Or S4 10-30 NOTE: Wait approximately 20 seconds or longer before disconnecting negative battery cable after ignition is turned off. - Disconnect negative battery cable. Drain engine coolant. Disconnect ISC valve connector. Disconnect air hose and 2 water by-pass hoses from ISC valve.
- Apply battery voltage between ISC valve terminals B1 and B2. Repeatedly ground ISC valve terminals S1, S2, S3, S4, S1 in sequence. See Fig 1. Check that ISC valve moves toward closed position.
- With battery voltage applied to the ISC valve, repeatedly ground ISC valve terminals S4, S3, S2, S1, S4 in sequence. See Fig 1. Check that ISC valve moves toward open position. If operation is not as outlined, replace ISC valve.