lights oscillate bright and dim whats going on

What are we workin on? Year model?

There are a few things that can cause this

Most common is a bad regulator on the older 69/ earlier systems

On any year or newer systems, this can be caused by a poor ground at the regulator, or by voltage drop in the harness supplying battery power to the regulator IGN terminal. You can set up an "oscillation" of sorts -- the bad connection in the harness is "just right" so that the regulator "thinks" the voltage is low, it ramps the voltage up, and the connection gets "made" so now the regulator "thinks" the voltage is high, and drops back down, thus repeating.

In rare cases, some high output ignition systems can generate enough EMI (electrical interference) to affect regulator operation.

This can also be caused by problems in the alternator, poor brush conditions, and sometimes stator insulation becomes bare from vibration---Sometimes you can SEE this. With the car in the dark, raise the hood and rev the engine while watching the alternator. If the stator windings look like a miniature lightning storm in there, the windings are shorting against each other.