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.
1993 Chevrolet C3500 HD 6.5 F, StandardFACTORY OEM SERVICE PROCEDURE
Electronic Air Control (EAC) Solenoid
- Turn ignition on, engine off. Disconnect EAC solenoid connector. Connect test light between solenoid connector terminals. See Fig 1. If test light comes on, check for grounded wire from solenoid to ECM. If wire is not grounded, replace ECM. If test light does not turn on, go to next step.
- Ground DLC. If test light comes on, check for faulty EAC solenoid connector. If connector is okay, replace EAC valve. If test light does not turn on, connect test light between harness terminal "A" and ground. See Fig 1. If test light still did not turn on, check for open in fuse or wire to ignition.
- If test light comes on, check for open in wire from solenoid to ECM. If wire is okay, check EAC solenoid resistance. If resistance is less than 20 ohms, replace EAC solenoid and perform ECM quad-driver check. See CONTROL UNIT under COMPUTERIZED ENGINE CONTROLS. If EAC solenoid resistance is 20 ohms or greater, replace ECM.
Factory Service Tools
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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.
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