SPN 524 FMI 3Electrical
Accelerator Pedal Position 1 - Voltage Above Normal or Shorted High
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 524 / FMI 3
Category
Electrical
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: The accelerator pedal assembly is mounted on the floor of the cab, driver side, typically near the firewall with integrated position sensors.
Common Symptoms
- Check engine light illuminated
- Engine runs at high idle or unintended acceleration
- Throttle position stuck at elevated level
- Engine derates or runs in limp mode
- Cruise control inoperative
- Unable to control engine speed with pedal
Root Causes
- Damaged or shorted accelerator pedal position sensor wiring harness Faulty accelerator pedal position sensor Corroded or damaged connector at accelerator pedal assembly Short to power in sensor circuit wiring Water intrusion or contamination in pedal assembly connector
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Derate Behavior
Power Derate
Yes
System Interactions
SPN 524 FMI 3 interacts with the following systems and may trigger cascading faults if not resolved promptly.
ECM communication — J1939 network faults can affect all connected modules
Engine protection — ECM may trigger derate to prevent damage
Aftertreatment — engine protection derates can affect regen strategy
Common Diagnostic Mistakes
Replacing the sensor without verifying wiring continuity and supply voltage first.
Clearing codes without identifying and resolving the root cause — the fault will return.
Ignoring related active faults — cascading faults often share a root cause.
Skipping the connector inspection — corrosion and damaged pins are a leading cause of sensor faults.
Condemning the ECM before exhausting all wiring and component tests.
Related Faults in This Category
OEM System Resources
ASE Training Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 524 FMI 3 — Full FSM Sequence & Repair Steps — includes wiring notes, sensor specs, and gated repair procedures.
Authority References
Diagnostic procedures on this page are informed by OEM service literature and industry standards.
Cummins QuickServe OnlineOfficial Cummins service manuals, fault code lookup, and TSB database.Detroit Diesel DiagnoCentralDetroit Diesel diagnostic procedures, DDDL documentation, and service literature.PACCAR MX Engine ServicePACCAR MX-11 and MX-13 engine service documentation and DAVIE diagnostic guides.Volvo/Mack Tech ToolVolvo and Mack engine fault code reference and PTT/Tech Tool diagnostic procedures.ASE — Diesel Truck Technician CertificationNational Institute for Automotive Service Excellence — T2 Diesel Engines certification standards.EPA Aftertreatment & Emissions GuidelinesU.S. EPA heavy-duty diesel aftertreatment compliance, DPF/SCR regulations, and NOx standards.
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