Supercharger (Boost) By-Pass Solenoid
WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2003 Mercury Sable, 2003 Mercury Mountaineer, 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition off. Disconnect Supercharger By-Pass (SCB) solenoid connector, located on rear of engine (F150) or on left front of engine (Mustang). Measure resistance between SCB solenoid terminals. If resistance is not 68-78 ohms, replace solenoid. If resistance is 68-78 ohms, IAC solenoid is okay. For additional testing and specifications, see TEST KJ: SUPERCHARGER BY-PASS CONTROL under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.