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 MANUALSCHEVROLET1982CITATION V6-173 2.8L VIN X 2-BBLREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSIDLE/THROTTLE SPEED CONTROL UNITDESCRIPTION AND OPERATION
1982 Chevrolet Citation V6-173 2.8L VIN X 2-bbl
Idle/Throttle Speed Control Unit: Description and Operation
1982 Chevrolet Citation V6-173 2.8L VIN X 2-bblSECTION Description and Operation
PURPOSE
On some models, idle speed is controlled by the Idle Speed Control (ISC) motor and ISC throttle switch.
ISC Motor Operation
The ECM monitors engine load--MAP--and engine speed--rpm--to determine the proper throttle opening.
The ECM then regulates engine speed by transmitting voltage signals to the ISC motor--opening or closing the throttle plates.
ISC Switch Operation
The ISC switch--mounted on the ISC motor housing--is closed when the ISC plunger contacts the throttle lever, and opens as the lever moves away from the plunger.
- When the switch contacts are closed the ISC motor controls idle speed.
- When the switch contacts are open the ISC plunger cannot retract.
On some models, idle speed is controlled by the Idle Speed Control (ISC) motor and ISC throttle switch.
ISC Motor Operation
The ECM monitors engine load--MAP--and engine speed--rpm--to determine the proper throttle opening.
The ECM then regulates engine speed by transmitting voltage signals to the ISC motor--opening or closing the throttle plates.
ISC Switch Operation
The ISC switch--mounted on the ISC motor housing--is closed when the ISC plunger contacts the throttle lever, and opens as the lever moves away from the plunger.
- When the switch contacts are closed the ISC motor controls idle speed.
- When the switch contacts are open the ISC plunger cannot retract.
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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.