I had a problem with the abs. It turned out to be a badly corroded factory join under the radiator. But the fact that your abs light comes on after you've driven it for a short time leads me to think, this is not the problem, as my abs light was on constantly, even on ignition. If you get the codes read and it comes up " Valve power supply , missing" then it could be the problem. If it is then the link above includes pictures that show how I sorted mine. Hope this helps Tom