My 98 gc gauges stopped working I found bad solder on cluster now all works except my speedo is incorrect.

 

I just solder what looked like bad joints on instrument cluster. Put back in all gauges work now but speedo reads wrong. It doesn't register until I do about 20 then it starts moving but is not correct speed. What did I solder that I shouldn't have?

 

It maybe just a bad circuit board. And soldering the circuit board isn't going to help. I would replace the circuit board.

 

Sometimes you get lucky with those and it's just the solder spot, but if the copper "trails" are degraded or the board has been flexed too much, you'll make it worse.