FORD 2013 F-550 v.1 - Manual (Page 101)

Solid illumination after the engine is started indicates the on-board
diagnostics system (OBD-II) has detected a malfunction. Refer to
On-board diagnostics (OBD-II) in the Fuel and Refueling chapter. If
the light is blinking, engine misfire is occurring which could damage your
catalytic converter. Drive in a moderate fashion (avoid heavy acceleration
and deceleration) and have your vehicle serviced immediately by your
authorized dealer.
WARNING: Under engine misfire conditions, excessive exhaust
temperatures could damage the catalytic converter, the fuel
system, interior floor coverings or other vehicle components, possibly
causing a fire.
Stability Control System
Displays when the AdvanceTrac®/Traction control is active. If
the light remains on, have the system serviced immediately.
Stability Control System Off
Illuminates when AdvanceTrac®/Traction control has been
disabled by the driver.
Transmission Tow/Haul
Illuminates when the Tow/Haul feature has been activated.
Refer to the Transmission chapter for transmission function
and operation. If the light flashes steadily, have the system
serviced immediately, damage to the transmission could occur.
4X2
Illuminates momentarily when two-wheel drive high is selected.
If the light fails to display when the ignition is turned on, or
remains on, have the system serviced immediately by your
authorized dealer.
4X4 LOW
Illuminates when four-wheel drive low is engaged. If the light fails
to display when the ignition is turned on, or remains on, have the
system serviced immediately by your authorized dealer.
100 Instrument Cluster
2013 F-250/350/450/550 (f23)
Owners Guide gf, 1st Printing
USA (fus)