What is this part?

[mattsmall1972]

Hi guys - I just picked up a Johnson OceanRunner 175 (I believe it's a 1993 model - the model number is really faint). I am in the middle of rigging it and I see that this is disconnected. I'm guessing it's a temp sensor - can you confirm if it is or not? Do I need to reconnect this? For reference, this is the port side of the motor - the prop is on the right side of this photo.

Thanks!

 

[racerone]

Sending unit for a temperature gauge.

 

[mattsmall1972]

Hi Racerone - thank you. I guess this is a dumb question, but will I need to hook this back up in order to get the temp, or is there some other magic that handles this when I hook up the red plug into the motor? Is this supposed to go through the red plug, or is there a separate wire for temp? I just don't know why it's not already hooked up into something.

 

[Ryan0186]

You should have a wire (not sure which color) that runs from the guage to the sending unit. Also need a ground at the guage and a power wire from the guage.

 

[mattsmall1972]

Hi Ryan - thanks. I can certainly hook this up, but I assume now that this isn't something that is going through the red plug. Is that correct? Do you know of any online wiring diagrams for this engine?

 

[Ryan0186]

Not sure what you mean by red plug? Should just be one wire that runs to the Sending unit. If the Sending unit is aleady on the engine I would guess that the PO prob stuffed the wire into the hull somewhere, maybe under consile or in gunwhale. I would trace any wires coming off the standing temp guage and go from there. You should have to mess with any wring under the cowl that is already hooked up.

 

[mattsmall1972]

I agree with you that I should not need to mess with any wiring under the cowl when rigging this, but the temp sender is definitely disconnected. The "red plug" is the one that connects to the boat-side wiring harness (see picture). Are you saying that the temperature sender does not send it's signal through the red plug? If it is supposed to, then I need to figure out which wire it connects to. If not, then I will have to run a new wire from here to the temp gauge in the dash. This motor was just placed on the boat on Friday.

 

[Chris1956]

Matt, I do not think that motor has any wiring for a temp gauge, to match that sender. You will find an overheat sensor wire, that will run to an alarm (System Check Gauge or at least a buzzer), in the harness thru the red plug.

I expect you will need to pull a new wire to drive the temp gauge on the dashboard.

 

[mattsmall1972]

Thank you Chris. So, just to be clear:

1) The temperature sensor in question does not run through the red plug harness
2) The temperature sensor in question goes to a temperature gauge, and I will need to run a new wire from this sensor to my temp gauge
3) There is a built-in overheat sensor wire via the red plug which is basically a "dummy light" which I can hook into a system check gauge and/or buzzer in the case of overheating.

Please let me know if this is correct.

 

[boobie]

You're correct.............

 

[Bosunsmate]

I just installed a temp gauge. I didnt want to run a new wire so i just used the tach wire that goes from the rectifier terminal board on the engine through the red plug to the controls. Theres a little outlet on most controls to access the tach wire, it normally has a positive and neg by it too that power on when keys on. I use my ears for a tach

 

[Chris1956]

Matt, You may have a wire for the trim gauge, that is available at your dashboard. If you are not using it, you can probably use if for the temp gauge sender wire. The trim gauge sender wire is likely white/tan, and should be mated with a purple and black wire, under the dashboard.

 

[mattsmall1972]

I'll be running a new wire for this since I also plan on using the trim gauge. Thanks all!

 

[Chris1956]

Matt, You can certainly do what you want, however, I have found that a trim gauge is not very important. They are usually difficult to interpret, and I have found that trimming by feel and ear is better than relying on the gauge.

I removed my trim gauge and replaced it with a water pressure gauge. Much more important than a trim gauge or a water temp gauge. Hopefully you have one of those.

Just my $.02.

 

[Grub54891]

Perhaps the sender was unhooked,because its shorted out. If so,you may have the alarm going off or the guadge wont work.

 

[boobie]

Agree with Chris above. Never did trust those trim gauges and the ears always worked better.