RPM GUAGE 150/HP, wiring without ruining the gauge

[nick petrilli]

Need to know where to get a diagram so i can connect a new rpm gauge. From my control box there are two purple wires which are both hot and two black wires and one grey wire. It's a 1989 OMC control box with a key on the back side of it.

 

[Daviet]

Re: RPM GUAGE 150/HP, wiring without ruining the gauge

I beleave the gray wire is the pulse wire for the tach.

 

[nick petrilli]

Re: RPM GUAGE 150/HP, wiring without ruining the gauge

That helps, Thanks. Why two black wires?

 

[emdsapmgr]

Re: RPM GUAGE 150/HP, wiring without ruining the gauge

Usually there is only one of each wire hanging from the control box-left there by the factory for future tach installation. The purple is positive, the black is neg, the grey is the tach signal wire. Those 3 will connect to the back of the tach and you are in business. Perhaps someone ran those extra wires so that they could run other devices, like a radio. Not a good idea-that engine only has a 20 amp fuse and it's not meant to run other devices-with the exception of a tach.

 

[Haffiman]

Re: RPM GUAGE 150/HP, wiring without ruining the gauge

Check that the purple wires are 'hot' only when ignition is ON.

 

[wilde1j]

Re: RPM GUAGE 150/HP, wiring without ruining the gauge

 

[nick petrilli]

Re: RPM GUAGE 150/HP, wiring without ruining the gauge

Thanks, you resolved my issue. I appreciate having the wealth of knowledge that this forum can provide. Nick P.