Idle speed control, general

Idle speed control is used to regulate the engine torque so that the balance between the torque developed by the engine and the torque required to keep the engine and its auxiliary equipment running is maintained.

Fig 1: Identifying Idle Speed Control Revolutions

Courtesy of SAAB-SCANIA OF AMERICA, INC.

The nominal idle speed is the number of revolutions per minute with a warm engine according to VEHICLE SPEED SPECIFICATIONS TABLE . Under certain circumstances the idle speed can increase to 900 rpm. This can occur e.g. at high load of the A/C compressor, power steering pump etc.

Idle speed control is active when the accelerator pedal is released and the vehicle speed is 0.

Fig 2: Identifying Idle Speed Control Revolutions Function Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.