2001 Ford Ranger ABS issue

I have a 2001 Ford Ranger. The brakes (rotors, calipers. Ect) were replaced last year.
The engine was replaced approx 3 yrs ago.

Last week my ABS light came on, but I didn't notice any issue with how it braked. Since then, the light hasn't come on at all, until today, for a few minutes, then the light shut off.

There is a wierd, almost burnt smell after I shut the truck off. I've only noticed it today, and it is strong enough to tell that it's not normal.

What is going on with my truck? Shouldn't any brake issues have been resolved when I got everything replaced last year?

It has about 46,000 miles on it.

Is this generally an expensive fix? I'm wondering if it's worth it to fix it or to replace it.