started truck up today and pulled out garadge and then the abs light stayed on and i noticed the pedle getting weaker ( likr no compression) so i figure broke line get out and look and driverside rear wheele is dripping fluid.... it was like runnin down the gas tank i think it was but i just looked quick cause its cold out... any ideas what coulda caused this?

 

The front to rear brake line probably rusted through, not uncommon.