Powertrain Controls - ECM/PCM

Diagnostic Chart.:

Idle Air Control Wiring.:

DESCRIPTION

The idle air control (IAC) consists of a two coil stepper motor controlling a valve. The motor is used to move the IAC valve pintle in and out of a seat to control the amount of air that enters the intake manifold at idle.

CODE PARAMETERS

Code 35 will set if:

^ Idle speed is greater than desired after PCM commanding the IAC motor closed.

^ Idle speed is less than desired after PCM commanding the IAC motor wide open.

DIAGNOSTIC AIDS

^ When attempting to diagnose an intermittent problem use the Scan Tool to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem. Select MALF History from Scan Tool EC menu.

^ Check the tightness of the female terminal grip with a spare male terminal.

^ Desired idle is based on a look-up table or anything that requires an idle speed boost will effect desired idle.

^ The desired idle speed can be found in either the Scan Tool or the SATURN Service stall system.

^ IAC is controlled by the PCM with four pulse width modulated (PWM) outputs.

^ Cruise cable misadjustment may cause a high idle due to throttle plates being held open.

^ Inspect PCV valve and system.