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Idle Air Control (IAC) Valve

WARNING: This page does not describe the selected car, but rather 18 other vehicles, including the 1995 GMC Vandura Special, 1995 GMC Vandura, 1995 GMC Suburban, 1995 GMC Rally Camper Special, and 1995 GMC Rally. However, it is still accessible from the selected car via links, so may be relevant.
  1. Disconnect harness connector to motor. Check resistance across IAC coil terminals "A" to "B" and "C" to "D". See Fig 1. Resistance should be 40-80 ohms. If okay, go to next step. If resistance is not as specified, replace IAC valve.
  2. Check resistance between IAC terminals "B" to "C" and "A" to "D". Resistance should be infinite. If resistance is not as specified, replace IAC valve.
NOTE: Functional testing of Idle Air Control (IAC) valve requires a scan tester capable of cycling ECM/PCM/VCM output devices (bidirectional) or a special IAC Driver and Noid Light Set (222L or J-37027). Flow charts in TESTS W/CODES - 7.4L article may refer to Tech 1 tester, General Motors' bidirectional tester.
Fig 1: Identifying IAC Valve Circuits (All Models)
G95D27709Courtesy of GENERAL MOTORS CORP.
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