Hello, today I was driving along when the gauges spiked, then dropped like when the car was off. (the tach and oil pressure stayed at where they were). The spedo is still working though. And my aftermarket tach still works.... Where does it all ground too? Does it have a fuse for it? Any advice or a simple wiring diagram for it. Any help is much appreciated .

EDIT: the fuel gauge is acting funny. It didnt drop. It just kept rising slowly.

Edit: the previous owners did a shitty job of re wiring the car. Put all new wires and it works now