2003 Chrysler Grand Voyager Brake warning light intermitten

I have a chrysler grand voyager 2003 limited edition, had an abs problem which i fixed it by changing the rear abs sensor. 2 days after I fixed the abs problem the car brake warning light started to come on when i put foot on the brake pedal and turns off approx 10 seconds after i take the foot of the pedal or with in 2-5 seconds after putting the foot on the accelerator. tried to retrive codes from computer but there is nothing there. your help in this matter will be highly regarded thanks
gavin