Join Date: Jun 2007
Location: Essex Connecticut
Ferrari Life Posts: 1,839
Places to look
1) check the connections on the back of the gauge
2) check the 5/8 crank sensor. The black lead is supposedly the tach input wire
3) check around the 5/8 ECU. I've heard stories about fuses being located there but they were on spiders.
After these your probably down to tracing wires looking for a short. I doubt a battery ground issue would show up in the tach only.
Previous owner of 348ts SS #64, Now Ferrariless