Tach not reading RPM

[Robado1967]

1999 130 saltwater series tach not reading right . Does not read rpm and sending mixed signals to overheat and low oil lights !!! I could use any help maybe bad ground???

[TownsendsFJR1300]

A bad ground or bad (corroded) battery cables will cause all kinds of issues.

I would start at the battery, remove/inspect/CLEAN terminals/cable ends. Don't just look at the connection, remove it, make sure its clean, some di-lectric grease, re-install. Same procedure for ALL the battery cables up to the engine.

If there's a a Perko type on/off/both switch, over time, they tend to loose their connection. If in doubt, by pass it..

Check the basic's first, please report back what you find..

Good luck..