70hp johnson rev counter wiring

[Toxicballsax]

I the boat I purchased ,has all of the gauges disconnected,so naturally I want them working .
The question is the Tacho ,has 3 plugs on the rear +,- and P .I would of assumed the + and - are the the power feeds and "P" being the pulse.But when + and - are connected the tacho swing right around to max RPM . SO what plug is what on the back ?
Also does the pulse wire come from the low voltage wire to coil 1?
Many thanks in advanced

 

[seasprayralph]

Re: 70hp johnson rev counter wiring

+ and - are as you say , p is also as you say "pulse" this is fed from the gray coloured wire in your panel, or if this is missing you can run a new wire spliced from the gray at your rectifier,, it is normal for the tacho needle to swing when ignition is switched on ,and should if working properly read correct rpm when engine starts

 

[Toxicballsax]

Re: 70hp johnson rev counter wiring

many thanks for the reply . I will fault finding tomorrow . I suspect I am missing the "pulse signal" .
Thanks again

 

[seasprayralph]

Re: 70hp johnson rev counter wiring

Just a thought,, the rectifier wire i spoke of may be actually YELLOW WITH A GRAY BAND,, cheers