FORD 2015 F-550 v.1 - Manual (Page 169)

System Indicator Lights and
Messages
WARNING
If a failure has been detected within
the AdvanceTrac system, the
stability control light will illuminate
steadily. Verify that the traction control
system was not manually disabled using
the stability control button. If the stability
control light still illuminates steadily, have
the system serviced by an authorized
dealer immediately. Operating your vehicle
with traction control disabled could lead
to an increased risk of loss of vehicle
control, vehicle rollover, personal injury and
death.
E138639
The stability control light
temporarily illuminates on
engine start-up and flashes
when a driving condition activates the
stability system.
The stability control off light
temporarily illuminates on
engine start-up and stays on
when you turn the traction control system
off, or if a problem occurs in the stability
system.
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Super Duty (), enUSA
Traction Control