Throttle Full Close Switch: Description and Operation

Throttle Switches And Throttle Valve Potentiometer:

Two throttle switches and a potentiometer are built into a single unit that is mounted on the throttle body. One switch is an idle switch and indicates to the ECM when the throttle valve is in the idle position. The other switch is the full throttle or wide open throttle switch ("WOT" switch), which indicates to the ECM when the throttle is in the wide open position. The signals from these switches help the ECM determine when to engage certain functions, such as idle speed control, deceleration fuel shut-off, full load enrichment and ignition timing controls.

NOTE: The throttle valve potentiometer signal is used ONLY for the automatic transmission ECM and does not influence engine controls or engine operation.

SELF DIAGNOSIS-IDLE SWITCH
The ECM compares the signal from the idle switch to those of the air mass sensor and engine speed sensor. If the idle switch indicates the throttle is in the idle position, but the signals from the engine speed sensor and air mass sensor do not confirm this state, then a fault code will be stored for the idle switch. Also, if, within the first 10 minutes of engine operation the idle switch does not close at least once, then a fault code will be stored.

SELF DIAGNOSIS-FULL THROTTLE SWITCH
The ECM compares the signal from the full throttle switch to that of the idle switch. If the ECM detects the full throttle switch and the idle switch closed at the same time, then a fault code will be stored for the full throttle switch.

There is no substitute signal for these inputs.