Idle Speed Control (ISC) System
- Warm engine to normal operating temperature. Ensure idle speed is correct. See ADJUSTMENTS article in the ENGINE PERFORMANCE Section.
- Apply parking brake and place transmission/transaxle in Neutral. Install jumper wire between terminals TE1 and E1 of engine check connector. See Fig 1.
- Engine RPM should increase to 1000-1200 RPM for 5 seconds, then decrease approximately 200 RPM.
- If engine RPM is not as specified, check ISC valve, wiring to ECU, ECU grounds and ECU. If engine RPM was within specification, remove jumper wire. Turn ignition off.
- To check ISC valve resistance, disconnect electrical connector from ISC valve on lower edge of throttle body. Using ohmmeter, measure resistance between terminal B+ and each remaining terminal. See Fig 2.
- Replace ISC valve if resistance is not within specification. See ISC VALVE RESISTANCE SPECIFICATIONS table.
NOTE:
Information not available from manufacturer for checking ISC valve operation for Previa.
ISC VALVE RESISTANCE SPECIFICATIONS
| Application | Ohms |
|---|---|
| Previa | 18.8-22.8 |