Colt L4-1597cc 1.6L SOHC Turbo VIN F FI (1988)
Idle Speed/Throttle Actuator - Electronic: Description and Operation
Idle Speed Control (ISC) Motor
The ISC servo consists of a motor, worm gear, worm wheel and plunger. Also, a motor position sensor to detect plunger position and an idle switch to
detect idle position are also incorporated. The worm gear, installed on the motor shaft, transmits motor rotation to the worm wheel. The worm wheel is
meshed with the worm on the plunger allowing the plunger to extend or retract as the worm wheel rotates. As the motor rotates in accordance with the
signal from the ECU, the plunger extends or retracts depending on the direction of rotation of the motor to actuate the throttle valve by way of the ISC
lever. This controls the idle speed by changing the throttle valve opening.