cannot get tach to work?

[jims3000]

i have a 1973 merc 115 and the manual and i have checked the wire diagramn and have wired up my tach according to the manual and it wont work.the tach worked with a evinrude does the tach have to be for a merc or could the switchbox be bad?

 

[pman7]

Re: cannot get tach to work?

A Merc manual gives directions for the old type of tach that gets it's signal from the switchbox.

If you have a modern tach, which is most likely, it should get it's signal from the alternator which means you hook your signal receiving wire to either yellow wire lead hooking into the rectifier.

At least that's the way my 71 Merc500 is and I believe your's is the same way. Someone will be along to verify this. Hopefully you haven't burnt out your tach. The voltage coming from that switchbox lead is quite high.

 

[jims3000]

Re: cannot get tach to work?

the tach i have came with the boat and it is a 1986 astroglass bass boat with the factory tach.would this be the newer style tach?

 

[ricksrster]

Re: cannot get tach to work?

Pman7 is correct. Set the little switch on the back of your tach to 6P.
here are instructions that work for the new tachs:
http://ww2.tflx.com/PDF/99320.pdf

 

[jims3000]

Re: cannot get tach to work?

thanks for the info.