Yamaha 703 Remote Control Wiring

Allan S

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Jan 31, 2020
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So I use a Yamaha 703 controller with a 2019 Yamaha T25 outboard. I want to get tachometer info (at the least) to my helm. I briefly had success bringing the outboard Command Link info to my helm chartplotter via NMEA 2000, but it stopped working, for some reason. Any thoughts on that would be welcome.

However, if I can't get the Command Link to work, I'd like to buy and install Yamaha analog gauges. The 704 controller has a pigtail with two sets of wires, one set of four (red, yellow, green black) which I believe attach to a tach, and a set of three (green, blue, red) which I think carry trim/tilt info.

If I go the analog gauge route, which analog gauges work with the wiring I've described? There seem to be several to choose from.
 

boscoe99

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In your first sentence you mention the 703 control box. Later on you mention the 704 control box. Which is it?
 

Allan S

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That’s precisely what I was looking for...thanks, boscoe99!

Quick question...what is the 6Y5-83653- cable going between the tach and the motor? Is that required for the tach and trim gauges to work?
 

boscoe99

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The 6Y5-83653- cable is for (1) the trim signal (2) the low oil pressure light ground and (3) the high engine temperature light ground.

The tachometer gets its RPM signal from the green wire in the ten pin harness.
 

Allan S

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OK, that’s what I thought. So I inspected my outboard today and there is no 4 pin connector to which the 6Y5-83653 cable would connect. There is only the 10 pin connector that goes between the controller and the motor. HOWEVER, on closer inspection and the right lighting, the two sets of wires that I described in my original email all seem to emerge from the 10 pin cable (near the controller) and the second set is NOT green, blue and red, but grey, green and pink. Could these three wires be carrying the trim, oil press and high temp info from the motor instead of the 6Y5-83653 cable?
 

boscoe99

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OK, that’s what I thought. So I inspected my outboard today and there is no 4 pin connector to which the 6Y5-83653 cable would connect. There is only the 10 pin connector that goes between the controller and the motor. HOWEVER, on closer inspection and the right lighting, the two sets of wires that I described in my original email all seem to emerge from the 10 pin cable (near the controller) and the second set is NOT green, blue and red, but grey, green and pink. Could these three wires be carrying the trim, oil press and high temp info from the motor instead of the 6Y5-83653 cable?

There is. You just have not found it yet.

Or it is already connected to a harness that runs to the helm.
 

Allan S

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How would I find out? My Yamaha T25 is a 2019 model. Is it possible they changed what connectors it has? I’ve ordered the service manual to see if it can tell me anything more. Is it possible that the 10 pin connector coming from the motor to the 703 controller is carrying the necessary info? That seems possible, because the 703 controller manual states that it can give high temp and low oil pressure alarms.
 

boscoe99

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I stand corrected.

It appears that the T25 has warning lights connected to the connector. The warning lights are at the front of the motor.

The trim sender wire (pink) should be connected to a four pin connector that is in the lower cowling.
 

Allan S

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I REALLY appreciate your input. However, your last reply really confuses me. I have a remote (not tiller) T25, and there are no warning lights on the front of the motor (there might be on a tiller version). In my setup with the remote T25 and the 703 controller, I assumed that when/if the motor overheats or loses oil pressure, the 703 controller gives an audible alert, carried through the 10 pin connector from the motor to the controller (that is what I read in my 703 controller manual. If true, that would imply that the bullet connector wires that exit the 703 controller might carry that same info, plus trim. I may be wrong.

I agree, I think the pink wire carries trim sensor data. There is a pink bullet connector wire at the helm that is pink.

I will look again hard and long for a 4 pin connector under the cowl. The only one I see is the Command Link 4 pin connector, which has only blue and white wires connected. I know that’s not the one.

At the very least, if I can’t figure this out, I know I can install a helm tack to the yellow, black and green wires, and not worry about getting the trim, oil and temp warnings to a gauge.
 

boscoe99

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What specific model do you have? What is the engine ID number?
 

boscoe99

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Parts catalog is showing a pilot light assembly at the front of the motor. I have an image but can't post it.

Wiring diagram shows the same.

Send me your email address via PM and I will send you the illustrations.
 

Allan S

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Boscoe99, you’re good! I had a chance to go to my boat today, and yes, my T25 DOES have the warning lights on the front of the motor, and the assembly that houses the warning lights is connected to a 4-pin connector, extremely hard to see under the batter cables and fuel line. You were right! So it appears that if I want these signals to go forward to the helm, I should get the 6Y5- cable as we talked about. This would disable the warning lights at the motor, but the signals would come to the helm, where one is more likely to see them.

I’m a bit uncertain about the 4 wire colors on that assembly, and what they do. From what I can see they are pink with black stripe, pink with white stripe, yellow with red stripe, and yellow with black stripe. Perhaps your wiring diagram addresses this?
 
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