Idle/Throttle Speed Control Unit: Description and Operation

Idle Speed Control (ISC) Motor:

DESCRIPTION
The Idle Speed Control (ISC) motor installed to the Throttle Body Fuel Injection (TBI) unit consists of a DC motor, gears, plunger and idle switch.

OPERATION
According to the signal from the Powertrain Control Module (PCM), the ISC motor moves the plunger to control the throttle valve opening. The Closed Throttle Position (CTP) 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 lever screw, the CTP switch sends an "ON" signal to the PCM. When the plunger is not in contact with the throttle lever screw, the CTP switch will send an "OFF," signal to the PCM.