i have i 95 f150, i hit a deer the other day at about 45. not even a scratch on the truck. about 4 days later the abs and brake light come on. fluid is missing from the master cylinder. i dont see any obvious leaks. the pedal is also very spongy and only seems to slow the car down at about 90 percent depression.

budro

 

Sounds like a brake line leak somewhere. I would first check in the area around where the deer hit. It may have caught a line in the process.

Sometimes as your brake pads wear to the end of the line your fluid level will drop to the point where it acts as if you have a leak somewhere. You could try filling the master cylinder back up and driving it some. If there is a leak, the level will go down and the brakes will continue to be weak.