Caterpillar Fault Code
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Engine Speed Won't Change
System
Controls
Symptom
Engine Speed Won't Change
Diagnosis & fix steps
LOGIC: Rotary Dial (Throttle) Bad Component.
ACTION: Disconnect the dial; if code stays, check the PWM signal line. Replace the rotary switch.
Red Seal field insights
Logic: ECM sees an "irrational" signal from the 10-position dial.
FIX: Replace the dial in the right-hand console.
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