So I just wanted to throw this info out because it could help someone. My instrument cluster on my 99 4wd blazer has been going crazy for a month or better now. All indicator lights would come on randomly. Tach was intermittent as well as speedo. Some mornings i would get in my truck to find my highbeam indicator illuminated without the key even in the ignition. As soon as I would start the truck every indicator light would light up and flash randomly the whole way to work. Also I would lose the digital gear selector and odo. as well.
I just dealt with it because it was just a little annoying and eventually would go away. I have put thousands of dollars into this truck over the years. This includes a new ignition switch about a year ago. My first though was that this was going bad. After all the proper tests I determined it was the instrument cluster itself not the ignition switch.
Well this week I started her up and had no digital gear selector, odometer, fuel gauge, and temp gauge. Time to deal with it now. I started with obvious first, connections. Pulled the cluster out nothing obvious moved to fuses. In the driver door fuse block i pulled fuse 4 which was gauges, nothing. I then put#4 back in and pulled #3 which is cruise control and everything worked. I can live without cruise until I can find a cluster but I can't without temp or fuel.
I don't know why it worked I haven't investigated further but it does in my case. Just wanted to start this thread in case it could help someone else in a pinch. Its not a fix exactly but it might get someone out of a pinch or down the road until they can replace the cluster.