Idle Switch (CADILLAC Except Brougham)

The ISC motor is equipped with an internal idle switch (also called a throttle or nose switch) which informs the ECM when it should be controlling idle.

Disconnect ISC connector. Connect an ohmmeter across Pink and Black/White wire terminals ("A" and "B") of ISC motor connector. See Fig 1. With throttle closed, continuity should exist. With throttle open enough to relieve tension from the ISC plunger, continuity should not exist.

Fig 1: Idle Speed Control Solenoid/Idle Switch Schematic

Courtesy of GENERAL MOTORS CORP.