4-Cylinder Idle Speed Control (ISC) System Test

Warm engine to normal operating temperature. Ensure idle speed is correct. Apply parking brake, block drive wheels and place transaxle in Neutral.
Install jumper wire between terminals "TE1" and "E1" of check connector located near left shock tower. See Fig 2 & 25. Note that engine RPM is maintained at 1000-1300 RPM for 5 seconds then returns to idle.
If engine RPM was not within specification, check ISC valve, wiring to ECU, and ECU grounds.
NOTE: Camry ECU is located in front of center console.
To check wiring and ECU, turn ignition on with engine off. With ECU connector plugged in, connect digital voltmeter between ECU terminals "ISC1" and "E1" from wiring side of ECU connector. Battery voltage should be present. Perform same test between "ISC2" and "E1" terminals. For more information on terminal identification, see appropriate wiring diagram in WIRING DIAGRAMS article or PIN VOLTAGE CHARTS article.
To check ISC valve, unplug ISC valve connector on bottom of throttle body. Using ohmmeter, measure resistance between terminals "+B" and "ISC1", and between "ISC2" and "+B". See Fig 1 Fig 2 & 25. Replace valve if resistance is not within 16-17 ohms.

Fig 1: Checking ISC Valve (3S-FE Terminals "E1", "TE1" & "T")

Fig 2: Checking ISC Valve (3S-FE Terminals "ISC1", "B+" & "ISC2")