Originally Posted by
benrover
OP,
I have a TD5 110 but have been having TC problems, I know the system are different however I think the same principle applies here. If you suspect that TC is not working, jack up the car turn it on then, try spinning one at wheel a time, the TC light will come on after you start rotating that wheel, if that wheel brakes TC is working on that wheel, if you see no TC light then you most likely have a ABS wheel sensor fault - this should be picked up by a scanner.
If you have low pressure at the brakes then if could be either the ABS pump or you have air in your modulator or lines. Does ABS give you a decent kick when you apply the brakes with one side on dirt and the other on tar? apparently the TD5's Wabco unit should, I assume your's is similar.