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Idle Air Control (IAC) Motor

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  1. Disconnect harness connector to motor. Check resistance across IAC coil terminals "A" to "B" and "C" to "D". Resistance should be 40-80 ohms. See Fig 1. If okay, go to next step. If resistance is not as specified, replace IAC motor.
  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 motor.
NOTE: Testing Idle Air Control (IAC) motor requires a "Scan" tester capable of cycling ECM output devices. Flow charts in the TESTS W/CODES articles may refer to the Tech 1 tester, General Motors' version of this tester.
Fig 1: Typical IAC Motor Circuit
G90I09033Courtesy of GENERAL MOTORS CORP.
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