tachometer install

[speegt]

trying to get my tach working, under the dash i found a 4 wire harness, brown, black ,white, white and purple. the white wire has power when key on using a volt meter, the white and p[urple shows a reading only when engine is running, would the white purple be my signal wire for the tach?the white wire im assuming would be my power wire for the tach the black a ground, and not sure about the brown this is the only wires not hooked up to anything.should you get a reading from the signal wire and if so what should it read using a simple volt meter? thanks

 

[ndaniels]

One should have power when the nav lights are on, too... you'll have one power with the key, a ground, and power with the nav lights turned on... the other one thats left will be the signal. I bet it is the white/purple, but thats an easy way to make sure.


On everything I have its a grey wire for signal.

 

[ckmate225]

I believe the white and purple should be for the trim sendernot the tach, but I don't know what cheges have been made over the years to that motor so...
You need to go back to the 8 pin connector and find the gray wire. (If the connector is numbered it will be #5), follow that forward and see if its been cut or spliced somewhere. That is your tach lead. you could run a jumper wire from the rectifier to the tach to test it if you want to, Hook up the jumper to the rectifier terminal with the yellow-red wire then to the tech lead on the tech. it should work if everything else is connected correctly.
But.. you should find the gray wire in the harness and trace it out and fix it with the more gray wire to avoid confution in the future.
Sometimes they are taped up under the gunnel somewhere if they wern't use originaly.
Good luck with it!! Let me know if you need more info.

 

[speegt]

tach

checked it out today traced the gray wire from engine to the bottom of control box runs right in there with 5 or 6 other wires, but the only wires coming back out are the 4 i mentioned earlier, a brown, black, white and white purple. those 4 wires are hooked to nothing previous owner of this boat had a tach hooked up but when they put new gauges in could not remember which wires went to tach,so how do i determine which wire is the signal wire.?

 

[ckmate225]

checked it out today traced the gray wire from engine to the bottom of control box runs right in there with 5 or 6 other wires, but the only wires coming back out are the 4 i mentioned earlier, a brown, black, white and white purple. those 4 wires are hooked to nothing previous owner of this boat had a tach hooked up but when they put new gauges in could not remember which wires went to tach,so how do i determine which wire is the signal wire.?

Check your PMs
Did you change the harness from a 5 wire to a 4 wire?
That gray wire terninates Just inside the plug on the front of that controller, You should only have 1 open port on that plug, "B"That should be where the gray terminates in the box, it does not connect to anything else in the control. You will need to add a 5th wire to that 4 wire harness, or cut the gray wire and bypass the controller. (thats a little bit hack but it willl not effect the performance).
-Ted
Call me if you need too.

 

[groundloop]

Let me see if I can confuse things more. An outboard tach has 3 wires going to it, the terminals are usually labeled "I", "G", and "S". "I" gets 12 Volts when the ignition switch is in the run position, that's normally the purple wire. "G" is ground, that's black. "S" is the signal, that's normally gray. Of course what's "standard" goes out the window if a previous owner decided to get creative.

 

[ckmate225]

Let me see if I can confuse things more. An outboard tach has 3 wires going to it, the terminals are usually labeled "I", "G", and "S". "I" gets 12 Volts when the ignition switch is in the run position, that's normally the purple wire. "G" is ground, that's black. "S" is the signal, that's normally gray. Of course what's "standard" goes out the window if a previous owner decided to get creative.

GL you are correct!! you never know what others have "fixed" in the past,
For Speegt's problem all his wires were correct just one(gray)wire was missing. So, I don't think you confused things at all, in fact it makes it very clear (to me). but I know what is running through my dyslexic mind, so if its not clear, I will write it another way.

Speegt's issue was;
The gray wire was missing from under the dash. it ran to the controller output plug (open pin "B"), so all the rest of the wires were there to hook up the tach, just not the signal(gray) wire from the controller output plug to the tach, It was just a matter of adding a single gray wire to the harness out of the control, So , all he needs to do is add the gray wire to the harness under the dash and connect it from the "B" output to the "S" terminal on the tach and he should be good to go.

Also, just for info, the gray wire does not connect to anything inside the controller but the output plug, so he should have a 5 wire output plug on the controller BUT, he only has 4 wires coming out of it.
If he cut the gray wire going into the controller and connected it to the 'S terminal on the tach it would be all set, I don't like cutting factory harnesses so I would add the gray wire to the output plug harness or at least, run a whole new wire from the rectifier to the 'S" treminal of the tach so I could leave the harness intact.

Tach wiring:
"I"= ignition (Purple)
"G"= Ground (black)
"S"= signal (AKA, the gray wire from the rectifier >to the controllers output plug"B"> to the tachs "S" terminal).

So if anybody wasn't confused before I'll be they are now.
(Dyslexics untie!!!)

 

[82Diplomat]

Maybe I can make things worse. When I hooked up my tach to a Merc 90, I got confused because there was a gray/white wire under the dash which is used for navigation lights. Your signal wire for the tach is the gray wire coming from the Voltage Regulator on the engine. My regulator has 2 yellow, 1 red, and 1 gray wire coming from it and it about a 3" square metal box with black or transparent potting material convering the circuit board.

When I traced my gray wire from the engine I removed all of the plastic wire loom and found my gray wire taped off after the main plug connector (between the engine and ingition switch but near the engine. Once I extended this gray wire to the tach as the signal wire, plus the power wires spliced from other gauges, everything was great...

 

[speegt]

tach

hey thanks for all the help , it turns out the gray wire goes into control box but its a brown for the signal coming out, and the new tach i got is no good , hooked up an old tach i had used the brown for signal after i checked to see there is continuity from the gray coming in to the brown coming out and wala i got a working tach. cant beleive this new faria tach dont work though sucks nice looking tach.

 

[rapidpulse]

hey thanks for all the help , it turns out the gray wire goes into control box but its a brown for the signal coming out, and the new tach i got is no good , hooked up an old tach i had used the brown for signal after i checked to see there is continuity from the gray coming in to the brown coming out and wala i got a working tach. cant beleive this new faria tach dont work though sucks nice looking tach.

Nice work!
Someone must have gotten in there and made that lead, factory wiring shouldnt even have had a brown wire.

sucks the tach didn't work but at least you got it figuered out.