MM U

What do the letters on the back of the switch stand for, specifically FL,HL,TL?

FL= Field Lights, headlights & tail light.
HL= Head Lights only.
TL= Tail Light only.

Good Luck

How do I wire for my lights? Currently I have one wire for the head lights (has low and high beam, they both work), and one wire for the tail light. How do I wire the HL? Thanks very much!!

What model tractor is this on? Doesn't sound like original MM U switch. Is this a light switch only, or lights/ignition combo?

Switch, is a combination ignition/lights. plate on tractor above the location of switch, shows stop,start,dim, bright, lights only.

Here is a picture I have of the back of a rotary switch. This is how it is wired on my tractor:

BAT is input. It connects to L terminal on generator voltage regulator. If you have an alternator or regulator with no L terminal it would connect to generator/alternator side of the ammeter

IGN is ignition, goes to coil

LTS goes to headlights and tail light. Head lights are single filament high beam headlights. Rear light is a combo bright light and red tail light with a rotary selector switch.

If Mag side is used you would not use the IGN connection.

I checked mine and it dims both front and rear light. The purpose of the spring looking resistor on the switch is to drop voltage for dim. I seldom use lights on mine so am not concerned that dim seems excessively dim.

If I understand correctly you have combination bright / dim sealed beams. If that were the case on mine I would run a wire from LTS to tail light, and another wire to center terminal on a double throw toggle switch then one side of switch to high beams, other side to low, then leave my ignition/light switch in Bright position and use toggle switch to switch between high and low beam.