abs -trac control

on my 01 .the warning only comes on when i put it in gear as long as i leave it in park it doesn,t come on and last night it wasn,t on at all, but know it stays on all the time after i put it in gear. the thing is i just bought the car ,i would not like to take it to the dealer just yet ,i did read other post on it ,but nobdy seem to know what the problem really is ,any help would be great.
thanks

This needs to be scanned with an abs function scanner for codes.