Idle/Throttle Speed Control Unit: Description and Operation

USED ON VEHICLES WITH UPGRADED EMISSIONS

Idle Speed Control Motor:

The Idle Speed Control (ISC) motor installed to the throttle body injection (TBI) unit consists a DC motor, gears, plunger and idle switch. According to the signal from the engine control module (ECM), the ISC motor moves the plunger to control the throttle valve opening. The idle switch, consisting of a hall IC, magnet and spring detects whether or not the ISC motor plunger is contacting the throttle lever screw. If the plunger is contacting the throttle screw, the idle switch sends an "ON" signal to the ECM. When the plunger is not contacting the throttle screw, the idle switch sends an "OFF" signal to the ECM.

NOTE: The throttle level screw are preset at the factory. The ISC motor must not be removed from the TBI unit or disassembled otherwise damage to the ISC motor and /or throttle may occur.