KE - Testing Notes

Idle Air Control Solenoid:

DESCRIPTION
The Idle Air Control (IAC) solenoid is used to control engine idle speed and dashpot functions. The IAC solenoid is mounted on the throttle body and allows air to bypass the throttle plate. The amount of air allowed to bypass is determined by the Powertrain Control Module (PCM) and controlled by a duty cycle signal.

Adaptive IAC Strategy
The Adaptive IAC strategy is designed to adjust the IAC calibration to correct for wear and aging of components. When engine conditions meet the adaptive strategy learning requirement, the strategy monitors the engine and determines the values for ideal idle calibration. The adaptive strategy stores these values for reference. These values are used by the PCM as a correction factor when controlling idle speed. The adaptive table is stored in Keep Alive Memory (KAM) and retains the learned values even after the engine is shut off. Diagnostic Trouble Codes 415 and 416 are an indication that the IAC adaptive strategy has reached its learning limits.

Whenever an IAC component is replaced or cleaned or a service affecting idle is performed, it is recommended that KAM be cleared. This is necessary so the idle strategy does not use the previously learned adaptive values. To clear KAM, disconnect the battery for at least five minutes. Once KAM has been reset, let engine idle for fifteen minutes (actual time varies between strategies). Otherwise, the vehicle may exhibit idle concerns until new adaptive values are learned.

NOTE
You should enter this Pinpoint Test only when you have been directed here from Diagnostic Routines or Pinpoint Test S.

REMEMBER
To prevent the replacement of good components, be aware that the following non-Electronic Engine Controls (EEC) areas may be at fault:

- Engine not up to operating temperature

- Engine over operating temperature

- A/C input (electrical problem)

- Throttle Speed Control Linkage

- Throttle Linkage

This Pinpoint Test is intended to diagnose only the following:

- Rpm in Self-Test only.

- IAC Adaptive Strategy Faults

- IAC Solenoid

- Harness Circuits: IAC and VPWR

- PCM