I'm looking for someone who may have had a similar problem or can help me troubleshoot this problem. My 1995 Newmar Dutchstar is on a Chevy p30 chasis with a 454cid engine. While either sitting still or rolling down the road, when the lights and/or AC with fan are turned on........the Speedo suddenly starts fluctuating like a tach. I have replaced the gauge cluster and the problem still persist. I have checked all the grounds, no blown fuses, everything works fine. My local RV guy cannot find the problem and none of the local Chevy dealers have any ideas nor do they want to take it into their shop. One web RV advisor said that my alternator was putting out too much?????? Anyone have any ideas?