I am trying to fix my tachometer for a 89 Camaro RS. I was curious if anyone knew the location of the ground cable for the tachometer if not all the gauges. I also would like any input on how to test out my gas gauge that seems like its not grounded out either. Both gauges are at 7000RPM/Full 24/7.

 

im sure you have the same problem all the tachs are having and thats a resistor burning out in a resistor block on the back of the tack. somewhere on this forum, i forgot now, i read what these resisors are suppose to read with an ohm meter and sure enough one of them was reading wrong. You cant get inside the block it looks like a chip and i believe it was white but i was able to strap a couple of resisors across where it was soldered to the board till i had the right resistance and now my tach works perfect. Im sure if you look around you can find that thread and fix it yourself.