FMI 5 — Current below normal or open circuit

The circuit is drawing less current than expected, or none at all — typically a break in the wiring or a disconnected device.

Start free J1939 (CAN) → canonical

Diagnosis

When you hit this

A sensor or actuator unplugged, often after service work.
A broken wire or corroded terminal.
A failed solenoid coil showing an open winding.

Resolution

How to fix it

Check what was recently serviced
FMI 5 appearing right after maintenance is almost always a connector left unplugged.
Measure coil resistance
For actuators, an open winding reads as infinite resistance and confirms the failure without further diagnosis.

Normalization

What Forge does about it

This code is reported by the device itself, so it survives normalization as data. Forge maps the vendor's fault register into the canonical fields alarm_code and alarm_description (and alarm_severity where the vendor supplies one), so an agent reads the same three fields whether the fault came from a Haas, a SINUMERIK, or a Cat engine. Forge does not clear the fault — that is the controller's job.