Guage Printed Circuit ??

[misternash2]

i'm going from a bad memory here. i repinned one from a 91 burb (electronic speedo) for my 85 when i did my 5.3 swap. it seems like there were 4 ground pins altogether. my guess is you have one bad one. could be a burned circuit on the printed sheet but i'd say broken/loose/corroded wire. follow the printed circuit from the 2 gauges. if they run to the same power supply/ground then your problem is likely in that wire. hopefully that helps you out.