Tach wiring,,, Help Please!

[MikDee]

Ok, since I have my boat a month or so, the Tach never worked, it appears to be a square factory tach matching the square speedometer, I just got a new 20pole tach from E-bay a smaller square one, that kinda matches, I noticed it's a Faria tach. Now the problem, when I took out my old tach there was a plug on it with 3 wires in a certain particular order, purple, grey, and black, the plug can only go on one way! When I looked at the back of the old tach, the purple was going to the "IGN" terminal. The black was going to the "GND" terminal, And the gray was going to the "SIG" terminal, The new tach is marked exactly the same way, So, is this the right order, or do I have to cut the plug apart, seperate the 3 wires and put them on different terminals? What is marked wrong here, Both the Faria tachs? or the original Bayliner factory plug wiring? As I understand it, Purple is SIGNAL, Black is GROUND, and Gray is POWER, or IGN. What's wrong with this picture?

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[burroak]

Re: Tach wiring,,, Help Please!

B=ground
G=Signal
P=Ignition

 

[MikDee]

Re: Tach wiring,,, Help Please!

burroak, As in my signature- 89' Force 125hp, the motor has purple coming off the rectifier, & terminal block, marked tach, I assume that's the signal going into the tach? There is a 3wire plug that slips onto the tach, but where the puple wire goes in, the tach is marked IGN???

 

[MikDee]

Re: Tach wiring,,, Help Please!

Is there something wrong with the Bayliner factory wiring? There
's only one way to insert the 3 pole plug into the tach? Or, is it the 2 Faria tachs, the old original one, and the new one, because both tach's terminals match, but the marked terminals don't match the boat's wiring colors?
The original tach hasn't been working since I got the boat, so I have no idea if it was ever wired in right? I spent all day making up a plate to mount the tach in the dashboard, and I was all set to plug it in when I noticed this, I need to get an answer so I can button this thing up, and move on to other issues, and I Don't Want To Fry My New Tach!

 

[Frank Acampora]

Re: Tach wiring,,, Help Please!

Usually, purple is the tach signal. What you need to do is to check where the grey wire connects on the wiring. Without knowing which control box you have, and whether the wires are in the box or if the switch is on the dash, it is difficult to sit here and diagnose. Purple wire on the engine and in the cable is not necessarily the same purple coming from tach. Remember: you have Bayliner wiring, Force wiring, and Faria wiring. If the purple on the tach plug is marked ign, then it needs to be hooked up to the ign. terminal on the switch. If the grey ultimately connects to the purple terminal on the engine and is marked sig, then it too is correct. And we all agree that black is always ground.

 

[MikDee]

Re: Tach wiring,,, Help Please!

Thanks Frank, the ignition switch is on the dash, as far as I know the 3wire plug is not marked? But can only plug in one way on the tach, and it looks wrong, it puts the purple wire on the (tach marked) IGN terminal on the tach, the black wire on the (tach marked) GND terminal, and the gray wire on the (tach marked) SIG terminal??? Unless I cut the connector to the plug, and put each wire on seperately, I cannot change the way it goes on.

So, you're saying the purple wire marked tach on the rectifier, terminal block, and engine wiring harness, may be a different color at the dashboard (like gray?) Does that mean that the igniton switch should have a purple wire going to the tach for the ignition terminal? And I'm guessing, the black wire going to ground in the middle is right?

I'll have to look closely at it tomorrow, and see if the plug is marked in any way, but I doubt it, also if I can trace the wiring to the switch, and to the motor, to see if the colors change along the way?

 

[QuadManiac]

Re: Tach wiring,,, Help Please!

Take an ohmmeter with a long wire attached to one lead, and with the ignition off, put one lead on the tach lead at the motor. Use the other meter lead to find which wire in your threesome is signal.

Then put one meter lead on your battery ground, and find which of the two unknowns left is ground.

The last unknown is 12V switched power (verify with the meter set to DC volts and your ignition on). Viola!

Good Luck!

Edit: even simpler.. use ohmmeter to find which wire is ground. Turn on ignition, use VOLT meter to find 12V. Wire left over is signal.

 

[MikDee]

Re: Tach wiring,,, Help Please!

Edit: even simpler.. use ohmmeter to find which wire is ground. Turn on ignition, use VOLT meter to find 12V. Wire left over is signal.

Good idea QM, I'll be doing that later, thanks,,, and to think, I was so happy, and anxious at the prospect of finally having a new working tach, and carefully fitting it to the dash, I almost plugged it in without looking, then wtf? everything came to a screeching halt, frustrating,,,lol

I'm so anxious to get the idle fixed, and get the boat in the water, I've had it to 40mph trimmed out, and the carbs were only opening 3/4 of the way! I also noticed the motor could come up some, because the cavitation plate is just below the hull, and if all goes well I'd like to get some boyesen reeds for it.

 

[MikDee]

Re: Tach wiring,,, Help Please!

Hooray! I have a smoother running outboard, and finally, a working tach! had it idling on the hose at 1,000rpm for today, anyway
I put my meter on each of the wires with the ignition on, and found only the purple to be hot, and the black to be ground, with the leads reversed the meter needle tried to read backwards, so I knew then the purple was (12V+), and the black was ground, no reading on the gray wire with the motor off, so I knew that was signal, It certainly did cause me to pause when I saw the wrong wire colors in the beginning? But, it all worked out, Many thanks to you guys for all the help!

Mike D.

 

[QuadManiac]

Re: Tach wiring,,, Help Please!

Congratulations!

So did the connector fit the new tach without any changes?

 

[MikDee]

Re: Tach wiring,,, Help Please!

Yes it did, it was exactly the same 3 poles in the same configuration, and marking, but in a slightly different spot. The dash light bulb had 2 blades sticking out? unlike the old tach with one, I figured one was a ground, sure enough it wouldn't work without my putting a slip on connector, and a small piece of wire to the ground terminal prong. My old tach was a 5" square 6K rpm, with a vertical rising needle, and left a 5" round hole in the dash, the new one is a conventional style 8K tach, but in a 3 1/2" square case, with a 3 1/2" round back, it was new! but, mighta been an older leftover different year Force tach, because it is adjustable to 20 pole.

 

[QuadManiac]

Re: Tach wiring,,, Help Please!

So there are 2 blades sticking out of the socket on the new tach, or two sockets openings on the old wiring connector?

 

[MikDee]

Re: Tach wiring,,, Help Please!

So there are 2 blades sticking out of the socket on the new tach, or two sockets openings on the old wiring connector?

Yes, but that's just pertaining to the backlight bulb, my boat wiring only had one blade connector.

Here's both tachs, the new one in place, the old to the right sitting on the dash, don't mind the dust,,, lol:

 

[burroak]

Re: Tach wiring,,, Help Please!

burroak, As in my signature- 89' Force 125hp, the motor has purple coming off the rectifier, & terminal block, marked tach, I assume that's the signal going into the tach? There is a 3wire plug that slips onto the tach, but where the puple wire goes in, the tach is marked IGN???

So...

B=Ground
P=ignition
G=signal

Yes? No?

 

[MikDee]

Re: Tach wiring,,, Help Please!

So...

B=Ground
P=ignition
G=signal

Yes? No?

:redface: Oops, guess you were right on burroak, thanks, but you don't waste words,,,lol

 

[QuadManiac]

Re: Tach wiring,,, Help Please!

Well, Mik - At least you got peace of mind by measuring first, connecting later, lol.

Regarding the 2 lugs on the new tach's light... do they both come from the removeable bulb mount assy, or is one on tach body and one on bulb assy? Is the tach body plastic back there? I'm going to assume so.

If you measure with your ohm meter across the two tabs, do you see around 5-10 ohms? If so, the old wire's spade goes on one tab, ground to the other. If it's well less than an ohm, they likely are the same side of the bulb and the extra tab is to daisy chain the light power to another gauge. If this is the case, use one tab for light power and you need to find the ground for the light eslewhere on the tach, maybe shared with the tach's main ground. You can Ohm that out too... One lead on one of the lights lugs, other on the gauge ground. should see 5-10 ohms.

Good Luck!!

 

[MikDee]

Re: Tach wiring,,, Help Please!

Well, Mik - At least you got peace of mind by measuring first, connecting later, lol.

Regarding the 2 lugs on the new tach's light... do they both come from the removeable bulb mount assy, or is one on tach body and one on bulb assy? Is the tach body plastic back there? I'm going to assume so.

If you measure with your ohm meter across the two tabs, do you see around 5-10 ohms? If so, the old wire's spade goes on one tab, ground to the other. If it's well less than an ohm, they likely are the same side of the bulb and the extra tab is to daisy chain the light power to another gauge. If this is the case, use one tab for light power and you need to find the ground for the light eslewhere on the tach, maybe shared with the tach's main ground. You can Ohm that out too... One lead on one of the lights lugs, other on the gauge ground. should see 5-10 ohms.

Good Luck!!

Q, That's what I did, I used a wire under the new tach's ground pole to ground one of the tabs to make the light work, curiously the old tach has the ground pole coming right through the brass plate attached to one side of the bulb, and the other tab for power, so it has a built in ground. The main thing is it all works.

 

[QuadManiac]

Re: Tach wiring,,, Help Please!

Great! Sorry, in my haste, I mistakenly read that the light wasn't working... not so.

Glad to hear you've got all your problems solved... Now get on the water!!!

 

[mtnlimo]

Re: Tach wiring,,, Help Please!

Wish I saw your post earlier... Went through the same thing with my tach..
Seems p= bat g= ground and gray= signal. Wire colors do change going through the plug. What made matters worse on my boat is tach there was a white wire labled tach that did nothing.. I plugged mine in and started it up and somehow it worked..

Glad to see you got yours going too