Fuse 16 and 7 blows when lights are on - 1999 Ford Windstar

Try disconnecting the battery and replace the fuse. There may be other electrical components tied into that fuse as well. Fuse 16 will control front and rear turn signals, back up lamps, BTSI solenoid and radio. Make sure you have the correct bulbs and fuse installed.

Body control module and ignition .

there is a short between the headlights and whatever is on 16 fuse

You will probably get a better answer if you repost and give the make, model, and year of your vehicle. But the most likely cause is a shorted wire to metal contact somewhere in the circuit that fuse protects. Check the owner's manual, if you have it, to find out everything that is on fuse #16, but assuming it is just for the tail lights: usually the tail lights are a separate circuit, no other circuits involved. The turn and brake lights are on a separate circuit for sure, as a safety precaution. So, somewhere between that fuse and the tail light socket, or including the sockets too, and the headlight switch, for that matter, there is a short that is blowing the fuse. Ever heard a little sparking under the dash, or smelled burnt rubber when the fuse started blowing?. Any snagged wires hanging from underneath? There are some neat electrical gadgets that help find shorts or bad wires, Fuse Buddy, Short Finder, things like that, kind of pricey, most of them, but you might find a reasonable tool. Otherwise probably a lot of digging, pulling harnesses apart to find wires, checking for power all along, etc., if you have to just start following a wire. Better invest in a multi-meter or a test light, and a wiring diagram would help to keep track of any changes in the wire colors you are following. See if you can unplug the bulb sockets at the tails and then see if fuse still blows. Finding shorts can get so frustrating it will chase you into bars-beware.

If the mains (line power) fuse goes when the vehicle is not connected, then suspect the charger.

If the fuse blows when connected.. make sure all lights and drive motor controls are first switched off.

N.B. Item 7.4.3 of the manual (see attached link) says the supplied power pack will not charge if below 16 Volts

and quote:
"If the battery voltage falls below 16
Volts, the batteries can no longer be
charged with the battery charger
supplied. In this case you must
contact your dealer"

(A technician would try charging each battery with a regular charger)

http://www.scootamart.com/media/manual/strider-midi-3-mobility-scooter.pdf

It is doing its job(blowing when there is more current flowing than there should be). What circuit is that fuse in? Whatever the load is(light switch, radio, etc) has an internal short or the wiring between the fuse and the load is shorted to ground. Also never replace the fuse with one that has a higher current rating. That's when you start melting wires and other things that you don't want to melt. Good luck!

the only thing that turns on the reverse light is the nuertral safety switch.

If i remember right those have tail light ciruit boards might be a short in that,

On the 2004 New Body style truck, the shift interlock switch is part of the BPP ( Brake Pedal Position ) switch.

Take a a look at the wiring on the switch to make sure it is not crimped / damaged some how. The wiring path is fairly short with the column shifter.

The shift interlock wiring path

Fuse #16 to BPP Switch is Tan w/ Red stripe wire
BPP to shift interlock solenoid is Pink with Light green stripe wire.

Pull the connector on the BPP, replace Fuse #16 ( if needed ) and jumper the back of the connector with a paper clip ( be careful not to make contact with ground, it will blow the fuse ) through the back of the connector.
If the fuse blows, the Shift Interlock Solenoid is the issue, if not the BPP or where the wires were located when the connector was plugged in is the issue ( that is part of checking the wire to / from the BPP for damaged insulation ).