it's fastened to the under side of the throttle body by 4 screws. so u gotta pull the TB.
you can test it first!
c/p from
http://www.autozone.com/autozone/homePage.jsp
"Bring the engine to normal operating temperature with transmission in N.
Using a jumper wire, connect the terminals TE1 and El of the check connector (DLC 1).
The engine rpm should rise to 1000 rpms for 5 seconds. Check that it returns to idle speed. If rpm is as specified, the valve is functioning properly.
If rpm did not function as specified, stop the engine and disconnect the jumper wire.
Disengage the ISC valve connector.
Using an ohmmeter, measure the resistance between the +B terminal (middle terminal) and the RSC and RSO outer terminals.
The resistance should be 21-28.5 ohms on a hot engine.
If not as specified, replace the ISC valve."
a free online manual for your vehicle can be found there. just sign up, plug in vehicle info and go to,
REPAIR INFO / 1998 TOYOTA CAMRY 3.0L EFI DOHC 6CYL REPAIR GUIDE / DRIVEABILITY AND EMISSION CONTROLS / ELECTRONIC ENGINE CONTROLS / IDLE AIR CONTROL (IAC) VALVE