Servicing the front brakes usually corrects pulsation in  the brake pedal. Service
the rear brakes only if the problem persists.
In order to determine if the front or rear brakes are at fault, test  drive
the vehicle. Drive the vehicle at low speed in an area away from people    and moving
traffic, such as a large parking lot. Apply the park brake and    feel for the pulsation.
If a pulsation is not noticed, the fault is probably    in the front brakes. When
the brake drums are removed, thoroughly clean  and   inspect the drums for the following
conditions:
Normal, light scoring of brake drum surfaces not exceeding 1.5 mm  (0.059 in)
in depth will not affect brake operation.