Hello everyone my name is Matt. I'm new to this forum and wanted to say hi to everyone before talking about what I'm experiencing. I just bought a 99 Blazer 4 door 4X4 with a blown engine. So I never had a chance to run through everything. Well after getting a new engine installed I was driving back home and noticed that whenever I hit the brake my stereo lights and compass/temp cluster go out. As soon as I'm off the brake there back to normal. When I turn my left turn signal on with my brakes on the indicator stay's solid when off the brake it flashes normal. My gas gauge will only read Empty with low fuel light on or Completely Full it just alternates between the two at different times. It doesn't matter what your doing just at random times it will change from Empty to Full or visa verse. Also my 4wheel drive worked once and it worked great but now no matter what button I push nothing works or even lights up. Could it be that unit needs replaced? I checked all the fuse's and all's good with that.

 

Sounds like you have some shorted wires under the dash. Since all of the brake and turn signal light operations go through the multifunction switch, I would start there.

 

I will thank you.