Nissan Repair: Tachometer, market model, randomness

Question
I have a 93 Nissan HB P/U 3.0L V6 4x4.  The tach Sometimes works, and sometimes does not,  it will also just wig out whenever.  As far as  I can tell there is no pattern to it's randomness.  Where should I start?

Answer
Hi Joe -

First of all, is this an after market model, or one already in the car?

I would check all connections for security. Ensure they are all tight (wiring).

Please get back to em whether it is after market - it helps with the diagnosis

Thanks
aloha
calvin