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Old 10 August 2012, 15:25   #1
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Yamaha 703 Control Box Wiring

I have searched but come up with very little. I have a Yamaha 703 control box hooked up to a Yamaha 85HP outboard. (no manual for the 703).
It has at some time been rewired and none of the instruments are wired up. I have an hour counter, RPM gauge and trim gauge. I have managed to hook up the hour meter using a feed from the yellow ign wire as I do know that the wires from the control box are as follows:
Red - Battery +
Black - Ground
Green - Tach signal
Yellow - Ignition on 12V

I have wired up the green to the tach 'send' terminal but can't test this just yet until engine is running.
Should I be wiring the red to the battery and the black to ground or does the control box obtain its power from the engine? The trim button works and moves the engine as it should.
The trim gauge has three wires plus a yellow that I think is also ign. All gauges are grounded to the battery.

There are also some other cables coming from the control box - grey, purple and I think it was Pink. Should these be wired up or left hanging with their little rubber bungs in!

In no expert electrician so a simple answer would help!

Many thanks,
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Old 11 August 2012, 14:00   #2
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This might help? (or not; didn't look at it too closely)

Wiring diagram/Manual for Yamaha 703 Control

jky
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Old 11 August 2012, 14:05   #3
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Or maybe this one?
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Old 11 August 2012, 15:58   #4
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Thanks, I found the first one but it does not seem to replicate what I am seeing! I shall have to get the tester out again I think. Thanks
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Old 12 August 2012, 18:28   #5
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I will pre-empt this with a Jura+memory warning!

Trim gauge should have signal, + and -. The other wire is probably a light feed.

There is a Yam tacho that seems to only need a signal and earth (and a light supply) . grey or green is the tacho signal, the one it isn't is the Suz wiring colour...

I will dig out the coherent info later if this just served to confuse.
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Old 12 August 2012, 20:00   #6
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Many thanks. Should I be connecting the red and black from the control box to the battery or do they supply + & - rather than require it?? I.e does the control box get power from the 10 or so wires in the large cable from the engine?
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Old 13 August 2012, 00:54   #7
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Pretty sure power comes through the harness from the motor.

jky
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Old 13 August 2012, 04:25   #8
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Thanks, hopefully it will all work then!
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Old 17 August 2012, 06:41   #9
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Quote:
Originally Posted by ajstars View Post
Many thanks. Should I be connecting the red and black from the control box to the battery or do they supply + & - rather than require it?? I.e does the control box get power from the 10 or so wires in the large cable from the engine?
The red & black at the control box essentially come from the battery, but via the engine. Theory being if you have a hard boat with the battery sat in a locker by the engine, you still have power to the dials etc at the wheel, potentially at the other end of the boat.

Having said that, you probably want to connect the tacho + to a Yellow. (switched +ve) so it only comes on with ignition & doesn't flatten your battery when the engine is off.

But yes, remotes loom or direct to batt are both valid, but connect via a switch & small fuse if you go straight to battery!
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Old 17 August 2012, 07:21   #10
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Thank you very much indeed. I shall now get to work on it.
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