SPN 1252 FMI 6ABS
ABS Modulator Valve - Rear Right - Current Above Normal
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DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 1252 / FMI 6
Category
ABS
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: The rear right ABS modulator valve is located in the ABS control valve assembly mounted on the rear axle or frame rail near the rear suspension.
Common Symptoms
- ABS light illuminated on dash
- Rear right wheel ABS function disabled
- Reduced braking performance in slippery conditions
- ABS fault code stored
- Trailer ABS malfunction indicator active
Root Causes
- Short to power in ABS modulator valve wiring harness Failed ABS modulator valve solenoid coil internal short Damaged or corroded connector at rear right modulator valve ABS control module internal driver circuit failure Chafed wiring causing intermittent short to battery voltage
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Derate Behavior
Power Derate
No
System Interactions
SPN 1252 FMI 6 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 1252 FMI 6 — 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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