Chart C-2A Idle Air Control (IAC) Valve Check

Diagnostic Chart:

Electrical Schematic:

CIRCUIT DESCRIPTION
The Engine Control Module (ECM) controls the Idle Air Control (IAC) valve to regulate the air bypass passage. The amount of the opening determines the idle speed. The IAC valve is regulated according to engine load. A stalling condition or rough idle could be caused by the IAC valve not functioning properly.

CHART TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. This checks if voltage is present at the IAC valve.
2. This checks the resistance of the IAC valve. Should be 11-14 ohms at 20°C (68°F).
3. This checks for an open coil in the IAC valve.

DIAGNOSTIC AIDS
An intermittent malfunction may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.