My 18’ 5.0 with 47K miles has been not wanting to restart when the auto on/off is engaged. As I sit at a light the engine cuts off and when its time to crank the starter acts like its dragging. It has done this once or twice from starting from park as well. Have checked the battery and its reading good. Its a motorcraft battery so Im assuming its the original battery which would seem to me its time to change it because of its age but its reading 13.6 volts when I check it. Just want to make sure its a starter issue before buying one.

 

I would change the battery first.

Especially if it's the original battery.

 

On these trucks, when you request a start, your signaling a Module to perform the electrical control function off a BUS request.
It's not a direct key to starter like the older truck of the past.
This makes the remote start function more compatible with the rest of the system.
I would put the dash display into engineering mode and look at the battery state of charge for being low in volts, then observe the cranking voltage for being low at less than 10 volts, then after running what the charge voltage is before just replacing the battery on hope.
S.O.C. should be 12.2 to 12.7, cranking voltage should not fall below 10 volts and running voltage should be in the 14.0 to 14.7 range depending on the battery age and initial state of charge at the time.
You have this diagnostic capability right off the Dash display.
Press the OK button and hold. Turn on the ignition switch on then wait a few second for the dash display to switch over. Operate the up or dn switch until the battery voltage comes up and go from there.
My feeling is from what you describe that a new Starter may be needed.
Good luck.

 

thanks for the information. I wasnt aware of an engineering mode. I will check on it first thing in the morning.