AI Diesel Tech

Fault Code Reference

SPN 1626 FMI 9ABS

ABS ECU - Abnormal Update Rate

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DVOM Testing — in guided session

Connector Pinout — in guided session

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Overview

Fault Code

SPN 1626 / FMI 9

Category

ABS

Derate Risk

No

Regen Inhibit

No

Inducement Risk

No

Component Location: ABS ECU is typically mounted on the frame rail near the wheel speed sensors or inside the cab chassis rail.

Common Symptoms

  • ABS warning lamp illuminated on dash
  • Traction control warning lamp active
  • Stability control malfunction indicator
  • Intermittent loss of ABS function
  • Communication loss with ABS module on CAN bus
  • Wheel speed sensor data dropout or erratic

Root Causes

  • CAN bus communication error between ABS ECU and other modules Faulty ABS ECU internal processor or software issue Intermittent power supply to ABS ECU Corrupted ECU calibration or firmware version mismatch Network termination resistor issue on CAN bus

Full step-by-step tests, DVOM guidance, and pinout data are available inside the AI Diesel Tech diagnostic session.

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Derate Behavior

Power Derate

No

System Interactions

SPN 1626 FMI 9 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.

Deep-dive diagnostic page: SPN 1626 FMI 9 — Full FSM Sequence & Repair Steps — includes wiring notes, sensor specs, and gated repair procedures.

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