Installed after market TTT gauges. Everything worked fine for about 6 months, now with nothing done to vehicle tach gauge suddenly stopped working , stuck on zero. Signal at coil good, signal at wire to gauge ( disconnected from tach good) seems to be grounded ok when I put back together because int light works . Any suggestions or further diagnostics. Thanks

 

Did you fuse the tach?

 

Yes .. Fused the Tach however I did not check it since the signal seemed to work with a tach dwell gauge connected to the wire. I'll check to see if the fuse is blown at next look.

 

Try the tach on a different car to see if the tach is the problem. I recently had the tach in my 62 go bad for no reason after almost five years of working fine.