I bought my '99 5.2 4x4 in 2009 with the brake and abs warning lights on and the abs nonfunctioning. I have read the threads about wheel speed sensors and other causes of these two lights being on, but that problem hasn't made it to the top of the list yet. But last week, on the day of our first significant snowfall, the lights went away and the abs worked! I slammed on the brakes on snow and ice covered roads and came to quick controlled stops with the familiar buzz in the brake pedal.

Does this suggest a different cause for my abs problem? It doesn't seem like a speed sensor would come back to life, but maybe a connection somewhere?

 

yea sounds to me like it was an electrical connection that came loose if it just came back on its own, or maybe (more likely) a loose ground

 

Yep, Check your connections!