SPN 1438 FMI 31ABS
Stability Control System - Condition Exists
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 1438 / FMI 31
Category
ABS
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: Stability control components include wheel speed sensors at each wheel hub, yaw and lateral sensors typically mounted on the frame rail, and the ABS modulator.
Common Symptoms
- Stability control warning lamp illuminated on dash
- ABS warning light may also be active
- Stability control system disabled or limited functionality
- No derate or immediate loss of vehicle control
- Fault logged during specific driving conditions or maneuvers
Root Causes
- Wheel speed sensor signal discrepancy or intermittent dropout Steering angle sensor calibration issue or signal fault Yaw rate sensor fault or mounting issue Lateral acceleration sensor malfunction ABS modulator valve internal fault or communication error
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Derate Behavior
Power Derate
No
System Interactions
SPN 1438 FMI 31 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
ASE Training Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 1438 FMI 31 — 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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