SPN 1088 FMI 6ABS
ABS Modulator Valve - Rear Axle Left - Short Circuit to Ground
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 1088 / FMI 6
Category
ABS
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: The rear axle left ABS modulator valve is mounted on the ABS modulator assembly near the rear axle brake chamber on the driver side.
Common Symptoms
- ABS warning lamp illuminated on dash
- ABS system disabled or non-functional
- Trailer ABS malfunction indicator active
- Reduced braking performance in slippery conditions
- Fault code logged in ECU memory
Root Causes
- Damaged or chafed wiring to rear axle left ABS modulator valve Moisture or corrosion in ABS modulator valve connector Failed ABS modulator valve solenoid with internal short Pinched or grounded harness near rear suspension components Connector terminal damage or improper sealing
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Derate Behavior
Power Derate
No
System Interactions
SPN 1088 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 1088 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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