FORD 2009 F-550 v.1 - Manual (Page 25)

Altering the severity of the driving conditions is recommended to lower
the transmission temperature into the normal range.
Red area (over temperature) —
the transmission fluid is overheating.
Stop the vehicle to allow the
temperature to return to normal
range.
If the gauge is operating in the Yellow or Red area, stop the vehicle and
verify the airflow is not restricted such as snow or debris blocking airflow
through the grill. If the gauge continues to show high temperatures, see
your authorized dealer.
2009 F-250/350/450/550 (f23)
Owners Guide, 1st Printing
USA (fus)
Instrument Cluster
25