Was towing my trailer this weekend w/ my 2001 F150 4.6L 2WD ext cab 63K miles. and my battery lamp started flashing when accelarating above 60MPH. the battery gage did not drop and was around normal location.
I just replaced all the ignition coils last week would that affect the alt or batt?
thanks for any help.

 

No relation between ignition and charge circuit.
Your ready to change out the alternator.
The brushes cannot follow the comutator from wear at higher rpm.
Good luck.

 

+1 for the Alternator