Need help with 1995 Johnson 90 tachometer wiring

Wcliff

Cadet
Joined
Aug 18, 2018
Messages
9
The tachometer on my boat was not connected when I acquired it. I'm trying to understand which wires connect from the engine to the tach. The back of the tach has several wires connected to it, but one of them is disconnected. I don't see a lose wire anywhere, and are the ones to the far left connected to a mounting bolt? Any help is appreciated folks!
 

Attachments

  • photo323478.jpg
    photo323478.jpg
    1.8 MB · Views: 2
  • photo323479.jpg
    photo323479.jpg
    1.7 MB · Views: 1
  • photo323480.jpg
    photo323480.jpg
    2.3 MB · Views: 1
  • photo323481.jpg
    photo323481.jpg
    2.3 MB · Views: 1

jhebert

Ensign
Joined
Jul 24, 2005
Messages
902
A TACHOMETER usually only requires four connections:

--a 12-Volt positive switched power via the ignition key switch, usually a wire with VIOLET insulation

--a negative return to battery, usually a wire with BLACK insulation

--the tachometer signal, usually a wire with GRAY insulation

--a gauge illumination 12-Volt power usually with a wire with BLUE insulation and controlled by a switch, if the gauge has illumination available

In your photograph of the rear panel of the tachometer, someone has turned the mounting studs into electrical terminal connections. That is a terrible practice in wiring.

In power distribution on a boat, a wire with RED insulation generally indicates battery positive 12-Volts. A wire with VIOLET insulation generally indicates a fused 12-Volts controlled by the engine ignition switch.

Your 1995 OMC engine appears to have the older big red Amphenol rubber multi-pin connector. The tachometer signal is carried in that connector on a GRAY conductor. The use of a wire with GRAY insulation to carry the tachometer signals is just about universal in outboard engine wiring. Many brands use GRAY for the tachometer.

The presence of an ORANGE conductor connected to the tachometer is confusing. Perhaps a prior owner or some dealer used the wrong wire color to bring the tachometer signal to the gauge.

See more about the usual OMC wiring at

http://continuouswave.com/whaler/ref...ionSwitch.html

See more about the usual wire insulation colors at

http://continuouswave.com/whaler/ref...rCode.html#OMC

The 1995 models from OMC were probably the last ones to use that big red rubber Amphenol connector. In c.1996 OMC changed over to their MWS or modular wiring system, and used a much different connector.

It is common on boats that have been around for a while for the wiring to be altered by the boat owner in rather unusual ways, and identification of a electrical conductor's purpose by just using the wire insulation color can be dangerous. Trace the wiring back to its source to determine what function or what signal is being carried on the wire.

Also, in some of your pictures there is evidence that the insulation on a wire had been damaged by inserting a probe. Do not puncture the insulation on electrical wiring on a boat. It just leads to problems.

The conductor with VIOLET insulation and a single-pole connector may be included in the engine wiring harness but not used on your particular engine.

If you plan to own the 1995 Johnson engine for some time and will be trying to work on it yourself, I recommend you get a factory service manual. The factory service manual will have excellent electrical diagrams.
 
Last edited:
Top