Lighting pulsing

[Jim wall]

I am having problems with my headlights pulsing even after the vehicle is warmed up and has run 20kms. It has had the alt. Replaced last Feb. And the batteries seem strong. It is an intermittent problem and as Murphy would have it, the problem does not show up when taken to the repair shop. This is a 2008 3500 Laramie with 109000 km s. Welcome any suggestions that you have

 

[Jack Davis]

check your grounds and your charging wire. that would be the first place i would look