I need a little help trying to find out what this sensor does. I'm not even sure the name of but it is mounted to the driver side frame rail in the engine compartment it has a brake line going to it there maybe another but cant really see but when i plug it in it starts to smoke so i have it unplugged it still drives fine but i would feel better if it was plug in if you have any idea please let me thank you

Its a 1993 f150 XLT 4x4 E4od trans

 

That's the ABS module. You're fine leaving it unplugged.