Larson/OMC Tachometer Harness

[timjohnston1]

I bought a 1995 Larson 16' Runabout with a 1984 Johnson 140. When I got the boat, the tachometer was non-functional and I took it out the other day to find that there was no harness/wiring hooked up to it. Does anyone know where I can get a harness for the tachometer shown in the attached picture?

http://img2.freeimagehosting.net/image.php?ca68489503.jpg

http://img2.freeimagehosting.net/image.php?8fb0c1435f.jpg

Thanks,

Tim

 

[jim_in_day]

Re: Larson/OMC Tachometer Harness

Thats a system check guage, its built into 96 and newer models wiring harness. since you have an 84 johnson its not part of the wiring harness and motor doesn't have the system check functions. Your best bet is to get a conventional tach and sell that one

 

[GlasV162]

Re: Larson/OMC Tachometer Harness

For your new tach, there is a wiring harness that plugs right into your control box. There should be a plug right below the ignition switch. The harness has a plug on one end and 3 wires on the other. The 3 wires are attached to the posts on the back of the gauge. It's a real simple rig--a lot easier than running wires back to the motor. By the way, the guage does not have to be OMC--I installed a Teleflex on mine and connected it using the OMC wiring harness.

 

[DJ]

Re: Larson/OMC Tachometer Harness

Advice by Glas is "spot on".

 

[GlasV162]

Re: Larson/OMC Tachometer Harness

Thanks DWJ.........at least I've been somewhat productive today!!

 

[timjohnston1]

Re: Larson/OMC Tachometer Harness

Thanks for the help. If I got the correct 8 pin connector for this gauge, could I hook it up so that only the tachometer would function? I'm not too concerned about the warning lights, but I would like to get this tach working if at all possible since it matches my other gauges.

If not, then I will go ahead and buy a new tachometer...

Thanks,

Kyle

 

[rickdb1boat]

Re: Larson/OMC Tachometer Harness

The Tach. will work once you get the harness. The pins may or may not be labeled. They are set up like this: You can probably rig it up without the harness if you can find suitable connectors for the pins...

1234
8765

#1 is Purple and will go to switched 12 Volts(Ignition)
#2 is black and will go to ground
#3 Is gray and will go to the gray wire (Tach. Signal)

Make sure to tape the other ones up so they do not touch if you use a harness...

 

[jim_in_day]

Re: Larson/OMC Tachometer Harness

I looked in the book today and couldn't find the wiring harness to adapt the tach to the 3 pin connector on the control box. If that part is available, it certainly would be a viable solution, I just couldn't supply a part number to Tim.

It would seem that if you could get a standard 3 wire harness, and then find the correct connectors to plug in the back of the tach, it would work, but finding those connectors might be a problem. I just made the suggestion based on the easiest possible solution

 

[timjohnston1]

Re: Larson/OMC Tachometer Harness

Okay, I got the tach wired up and I tested it…works great! Thanks again for the help. Here is a picture of the setup:

http://img2.freeimagehosting.net/image.php?187c59a776.jpg

However, I tried to find the signal wire under the dash/near the controls and I couldn’t find one. I did find a gray wire under the dash that wasn’t connected to anything, but I tried using it for the lead and it didn’t work. I fished around the engine and found that the only place where I can find a signal that will make the tach work is the terminal on the strip seen here:

http://img2.freeimagehosting.net/image.php?e3b9d63a15.jpg

Then I noticed that these 3 pin connectors were not connected as seen in the pictures below.

http://img2.freeimagehosting.net/image.php?89a1288005.jpg
http://img2.freeimagehosting.net/image.php?ecc62d305a.jpg

I am running a 1984 Johnson 140 and the only modification is that the VRO has been disconnected. Should these be connected? Would that have any chance of making the gray wire work so that I wouldn’t have to run a wire back to the terminal strip in the engine?

Thanks for any help,

Tim

 

[jim_in_day]

Re: Larson/OMC Tachometer Harness

Tim, the 3 pin connector we are talking about is on your control box under the key switch. You did a wonderful job of connecting the wires on the tach, I am impressed with your handiwork. How the wiring works on your boat is that the signal from the tach is in the wiring harness that plugs into your control box, and then internally in the control box the ground, key power, and tach signal goes to the 3 wire plug in the control box. I would also fill the back of the tach with silicon sealer to keep moisture out since you don't have the plug for it installed.

 

[timjohnston1]

Re: Larson/OMC Tachometer Harness

Thanks for the compliment jim in day. Thats a good idea about filling the back with silicone.

I'm still unsure of where to look for the tach signal wire. My key switch is located on the dash to the left of my steering wheel and my controls are on the right, so which side should I be looking on? Is there any other color the signal wire could be besides gray?

Tim

 

[jim_in_day]

Re: Larson/OMC Tachometer Harness

Ok tim, the first thing we need to do is look at the control box. Is it a single handle control box? on the side of the box facing the back of the boat is where your control cables for your throttle and shift are. Right in that area is where the plug in should be. If not, we can go from there

 

[timjohnston1]

Re: Larson/OMC Tachometer Harness

Jim,

I went home last night and ran a wire back to the motor so everything is all hooked up and working well. I figured I could spend my time tracing wires until I was blue in the face or I could just take a few minutes to run one back to the motor and be done with it. Life is good!

Thanks again to everyone for the help.

Kyle