I have a 2000 Blazer.I'm having a problem with the right side headlight and highbeam.The lights stay very dim,but the left side lights work fine.Any help would be appreciated.Thanks,Mike

 

Are both low beam and high beam affected?

It is possible that the daytime running lights relay has failed in the open position which ties the driver side low beam and high beam into parallel operation. It could also be the headlamp grounding relay stuck in the closed position.

Here is a conglomeration of schematics that I just put together and marked up:

It is quite a confusing setup, but check out the daytime running lights relay. Swap it with another 5 pin relay of the same size in the underhood fuse block and see if the problem goes away.

 

I replaced the day time running lights relay.Having the same problem.Do you know where the headlamp grounding relay is located.Thanks