SPN 3517 FMI 4ABS
Brake Lining Temperature Sensor - Voltage Below Normal
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 3517 / FMI 4
Category
ABS
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: Brake lining temperature sensor is typically mounted on the brake caliper or integrated into the brake pad wear indicator assembly on the axle.
Common Symptoms
- ABS warning light illuminated
- Brake temperature monitoring inactive
- Fault code stored in ABS ECU
- Possible reduced brake retarder effectiveness warnings
- No active brake temperature gauge reading
Root Causes
- Shorted brake lining temperature sensor Damaged wiring harness between sensor and ABS controller Corroded or moisture-damaged sensor connector Faulty ABS control module input circuit Grounded sensor signal wire
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Derate Behavior
Power Derate
No
System Interactions
SPN 3517 FMI 4 interacts with the following systems and may trigger cascading faults if not resolved promptly.
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.
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 3517 FMI 4 — 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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