Tachometer wiring

[rebars1]

When I got my boat (1971 Trisonic Merc888 Ford 302) I noticed the brown tach wire was not connected to the coil. I connected it to the negative post and it worked, sometimes. While cleaning the wire connections I noticed on the back of the tachometer there is a brown wire to the center post, a white wire to the light, and a red wire, which runs to a center post on one of the gas guages, which I think goes to a ground. My question is should that wire be connected to a ground or to a positive 12v wire? There has been a lot of re-wiring under the dash by previous ownwers so I don't necessary trust all of the wire colors for function (red=positive, etc.)

 

[trog100]

Re: Tachometer wiring

"and it worked, sometimes." being incorrectly wired would not tend to have "a work sometimes" effect.. faulty instruments or intermittent contacts tend to do that..<br /><br />i know that when i look at the back of my dash panel.. every instrument and switch seems to have six times as many wires sprouting from it as my logic tells me it should have.. i dread going near it.. he he <br /><br />trog100

 

[waterone1@aol.com]

Re: Tachometer wiring

I agree with Trog, if it works sometimes, it's not a problem with the way it is wired. Besides checking for loose or coroded connections, see if the tach has a multi position switch on the back of it to select how many cylinders the engine has. Those switches are prone to get "dirty" and cause the tach to become intermittant. Just flip or rotate the switch back and forth a few times...that will clear up the problem.

 

[rebars1]

Re: Tachometer wiring

Thanks guys. I was going to install a new wire directly from the side post to ground (or positive),(center post comes from coil), because I'm not confident with what happens to the circuit after it connects to the gas guage post. I wanted to verify that it should go to ground or to positive. Also, is there a way I can test the tachometer to see if the meter itself still works? You are right, trog100, it looks like someone threw a bowl of wire spagetti up there!

 

[blackz3]

Re: Tachometer wiring

LOL my brotherinlaws dash hasnt worked since he desided to pressure wash it!!! told him id have a look. FORGET about it already...aint that many wires in the dang space shuttle!!!!!!

 

[rebars1]

Re: Tachometer wiring

Can anyone verify if the wire to the side post should go to ground or positive? The center post wire comes from the negative side of the coil. The wiring diagragms in Seloc aren't clear to me.

 

[rebars1]

Re: Tachometer wiring

Well, I hooked it back up to the coil and it is working! Go figure...