Ford Super Duty Owner's Manual page 180

Auxiliary Power Points 179
The power point can switch to a fault mode when it is overloaded,
overheated, or shorted. Unplug your device and turn the ignition off then
on for overloading and shorting conditions. Let the system cool off, then
turn the ignition off then on for an overheating condition.
The power point can provide power whenever the ignition is on and the
indicator light is on. The indicator light is located in the top left corner
of the power point.
When the indicator light is:
• on — power point is ready to supply power
• off — power point power supply is off; ignition is not on
• blinking — power point is in fault mode.
2013 F-250/350/450/550 (f23)
Owners Guide gf, 1st Printing
USA (fus)