Operation CHARM
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GMC Truck
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1983
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S15/T15 4WD Jimmy V6-173 2.8L VIN B 2-bbl
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Repair and Diagnosis
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Relays and Modules
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Relays and Modules - Powertrain Management
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Relays and Modules - Fuel Delivery and Air Induction
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Idle/Throttle Speed Control Unit
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Description and Operation
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Idle Speed Control (ISC)
Idle Speed Control (ISC)
The
ISC
assembly controls engine idle speed according to ECM programming.
When the throttle lever rests against the
ISC
plunger, the ISC acts as a dashpot on throttle closing per second.