ABS after lower spring install

The other day I installed a set of lower springs on my 2000 GT. After everything was put back together I had the ABS light on before I even got out of the driveway. I took everything apart and found one the had a bunch of crap stuck to it and cleaned it off. This morning I took it to work. It stayed out the whole 20 min. drive to work untill I pulled in a parking space and then it popped back on. I'm not sure why it would do that? Any ideas?

Ever since it came back on it has stayed on steady. All the wires looked fine when I checked them before. I have no idea what I could have done.

Are they that fragile? Could they be broken without looking bad from the outside? Is there a way to test them?