SPN 3600 FMI 2ABS
Pneumatic Supply Pressure Sensor - Erratic/Intermittent Signal
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Overview
Fault Code
SPN 3600 / FMI 2
Category
ABS
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: The pneumatic supply pressure sensor is typically mounted on the air supply manifold or governor assembly near the ABS control valve.
Common Symptoms
- ABS warning lamp illuminated on dash
- Intermittent ABS system deactivation
- Erratic air pressure gauge readings
- ABS system cycling on and off unpredictably
Root Causes
- Faulty pneumatic supply pressure sensor Corroded or damaged sensor wiring harness Intermittent connector contact at sensor Water or moisture intrusion in sensor connector Loose sensor mounting causing vibration-induced signal loss
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Derate Behavior
Power Derate
No
System Interactions
SPN 3600 FMI 2 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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OEM System Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 3600 FMI 2 — 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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