low brake pad light on dash won't go off.

What is your question?

Replaced the front and rear pads and rotors on a 2006 mercedes r350. after about 2 miles brake light on center counsel came on and won't go off. Checked sensor it was installed properly. Checked and found 5 volts power going to rear sensor and was told there should be none. Is this true and if so what parts and procedures are required to fix this problem.