Hi,all.I have a 2001 s-10 blazer with an electrical problem.When I start the truck all the lights(head,tail,dash,dome,ect..) blink or flash.It isn't on-off but dims slightly and then gets bright again.It flashes fairly quick.It really isn't noticeable at idle.I am a truck mechanic and haven't ran into this problem on a big truck yet.I was leaning toward a ground or short but hitting a bump dosen't effect the problem.Could it be coming from the alternator?I have checked for past codes and found none.Any help is greatly appreciated.

How long do they do this? It could be a poor ground or a low voltage problem.