low trac light at highway speed only
 

hello I own a 2001 alero and for a year or so now like clock work as soon as I reach 67 mph the low track light comes on and lowers the power to the engine till I go bellow 67 mph or turn off trac control I have 4 new wheel bearings I have used a 6 volt battery and check for broken wires still no sign of the problem any ideas on the matter would be great, thanks barry