I have a 99 Silverado with over 140,000 and a little while back the odometer started flickering and would go off and on. Then it got to the point where it mostly stayed off or would read 388,607 but would not keep counting the miles. Now if it comes up at all it reads all zeros and is in kilometers instead of miles. Now the most recent thing is the tach, speedo, and fuel gauge along with my 4x4, cruise, and high beam light staying on all the time. The cruise still works as well as the 4x4 and the high beams are not on. If I start it and then shut it off, the three lights will go out but as soon as I restart or open my door the lights come back on. When the 4x4, cruise, and high beam lights are on, the fuel gauge reads empty, the speedo is off, and the tach is way off from the actual engine speed. My idle is normally at 500 and now the tach will read 1000. When actually driving the tach will read between 3500 and 4000 before shifting and if I jump on it the tach will peg out and sit there but the engine doesn't sound like it is at those rpms. For the most part I hear I need a whole new cluster but I've also heard that it could be my ignition switch or possibly a vehicle speed sensor. I don't really want to put a lot of money into it but it needs to be fixed. Has anyone had this problem? Solutions and cost? Any help is much appreciated.

 

I'd start with a cluster if it were me. Do you have the GMT400 OBS style truck or a truck with a 5.3L engine?

 

Could be a body control module. That isn't the same as the vehicle control module (VCM), which is in charge of the power train; it handles the vehicle's lights and dashboard components. If it, or a connection to/from it, is going bad, it may cause some of the problems you are experiencing. Not sure where it's located, but do some research and check the connections going to and from it and into the cluster.

Beyond that, it's something a dealership will have the tools to diagnose. Unfortunately, replacing them is expensive, as they need to be flashed (programmed) to operate on your vehicle, thus you can't just buy, plug, and drive.