Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1997CHEVY EXPRESS G3500, VAN CARGO, 6.5 FREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 20 (ENGINE CONTROLS - SYSTEM & COMPONENT TESTING - 5.0L)FUEL SYSTEMIDLE CONTROL SYSTEMIDLE AIR CONTROL (IAC) VALVE
1997 Chevrolet Chevy Express G3500, Van Cargo, 6.5 F
Idle Air Control (IAC) Valve
1997 Chevrolet Chevy Express G3500, Van Cargo, 6.5 FSECTION Idle Air Control (IAC) Valve
WARNING: This page is about a different variant/trim than selected.
- 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.
- 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 bidirectional scan tool capable of cycling PCM/VCM output devices or a special IAC Driver and Noid Light Set (222L or J-37027). Text in TESTS W/CODES - 5.0L
article may refer to Tech 1 tester, General Motor's bidirectional scan tool.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.