An idle stop solenoid is an electrical device that closes off the throttle to prevent an idle engine from continuously running once you turn off the key in the ignition.. All 68 GTOs had the Idle Stop Solenoid. It is powered from the ignition switch 'Run' circuit through the lower right fuse in the fuse box. Always on when engine is running. It is (was) intended to prevent engine run-on when turning the key to off, which was a problem with the factory emission system. To make it work correctly, the engine idle is set using the solenoid screw, and the carburetor.
The idle stop solenoid screws on the carburetor. It sort of over rides the idle adjustment screw. What it does is completely close the carburetor in an attempt to prevent dieseling after you turn the car off.. C3 Tech/Performance - connection for the Idle stop solenoid - Late 77 L 48 Where does the electric connection for the Idle stop solenoid come from? I have just rebuilt my Q-jet and the ISS was not connected ever since i have owned the car. The only diagram showing ISS is the A/C wiring diagram, and I do have a double.