Idle Speed Control System: 3.0L
- Listen for clicking sound at ISC valve immediately after engine is shut off. The ISC valve is located on air intake chamber, near throttle body.
- If no sound is heard, check ISC valve and wiring circuit between Electronic Control Unit (ECU) and ISC valve. See appropriate wiring diagram in WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section. The ECU is located near the glove box.
- To check ISC valve resistance, ensure ignition is off. Disconnect electrical connector from ISC valve. Note ISC valve terminals. See Fig 1.
- Using ohmmeter, measure resistance between specified terminals. See ISC VALVE RESISTANCE SPECIFICATIONS (3.0L) table. Replace ISC valve if resistance is not within specification.ISC VALVE RESISTANCE SPECIFICATIONS (3.0L)
Terminals Ohms B1 To S1 Or S3 10-30 B2 To S2 Or S4 10-30 NOTE: Before removing ISC valve, drain coolant from cooling system. Remove both coolant by-pass hoses. - To check ISC valve operation, remove ISC valve. Apply battery voltage to terminals B1 and B2. See Fig 2 and Fig 3 . Repeatedly ground terminals in sequence and ensure ISC valve closes and opens. See ISC VALVE GROUNDING SEQUENCE table. Replace ISC valve if defective.
ISC VALVE GROUNDING SEQUENCE
| Application | Terminal Grounding Sequence | |
|---|---|---|
| 3.0L | ||
| To Close ISC Valve | S1-S2-S3-S4-S1 | |
| To Open ISC Valve | S4-S3-S3-S1-S4 | |
| All Others | ||
| To Close ISC Valve | S1-S2-S3-S4 | |
| To Open ISC Valve | S4-S3-S2-S1 | |