Yamaha 3 wires from control box - redundant?

[Polwart]

(JK if you think this is really an electronics q. rather than engines please feel free to move this).

My Yamaha control box has 3 wires (black/yellow/green) which come the box, in addition to the main wiring loom. I have never hooked these up to anything (principally because I originally worked on hand start, then when I added a battery it didn't seem to need these - OK its because I'm lazy )

As I understand it they provide power simply to test the alarm circuits before starting the engine. My limitted knowledge suggests they really just test the buzzer is working and don't provide any useful knowledge on the temp/oil level.

Should I get up off my lazy ass and wire them in - or are these really just redundant?

[Nos4r2]

You'll never know if your buzzer stops working if you don't...

[Polwart]

Originally Posted by Nos4r2

You'll never know if your buzzer stops working if you don't...

mmm... thanks Nos... I guess I realised that. Is this a common problem? i know it works at the moment as I had a low oil alarm recently (it goes off about 2 hours before it runs out!).

the other thing that puzzles me about these wires - is why don't they get fed power through the main loom?

[Polwart]

OK the plot thickens - and now I know little more - thanks to the power of google - but now I am also confused.

The wires don't appear to power the alarm test function at all.

The black wire is not surprisingly connected to ground (battery neg)

The yellow wire becomes 12V+ live when the key is turned to the on position. This makes sense to have as a feed from the control box - although I don't have any obvious applications for it.

The green wire is at 0V with the key in the on position, but goes upto 1-2V when turned to start. Boat is in the garage just now, so I couldn't put the muffs on it but I suspect this might be a tacho output? Again it would make sense to have this as an output at the console. If this is a techo output is there a simple Volts to Revs conversion, or do I need a genuine Yam tacho. I don't need one routinely - but it would be nice to know if I am getting max rpm - so best prop.

So all this leads to another question - if these don't need connected to get the buzzer test at start up - is something wrong if I don't have the buzz?

The control box is the fairly standard 703 side unit, with no power trim and tilt switch.

Thanks in advance for any advice.

NEIL

PS if anyone from Yamaha ever reads this - why is this not obvious in the installation manual?

[Nos4r2]

Originally Posted by Polwart

mmm... thanks Nos... I guess I realised that. Is this a common problem? i know it works at the moment as I had a low oil alarm recently (it goes off about 2 hours before it runs out!).

the other thing that puzzles me about these wires - is why don't they get fed power through the main loom?

Sorry-I know that sounded a little flippant. It's sod's law though that the day you overheated with a poly bag around the leg would be the day that you found out the alarm wasn't working.

[mdt]

Originally Posted by Polwart

PS if anyone from Yamaha ever reads this - why is this not obvious in the installation manual?

Because that would take both all the fun out of it… and you would not learn things…

[Daniel]

the 703 has three wires for connection of a tacho

+12v
Gnd
Signal

I don't remember the colours, it was 5 or more years ago i wired one up

Any marine tacho (QuickSilver (Merc) & Yam for sure) will do so long as it supports the right mode - and that depends on your engine and ignition system. Most marine tachs have a switch which relates to cylinders and other stuff! I think most modern engines work on the same setting but it escapes me.

[Daniel]

You can easily test your warning horn (buzzer) by grounding the temp sensor wire at the engine end (need ign on)

again the colour escapes me i am afraid but it is obvious, it's connected to the big brass temperature jobbie

[Polwart]

Originally Posted by Nos4r2

Sorry-I know that sounded a little flippant. It's sod's law though that the day you overheated with a poly bag around the leg would be the day that you found out the alarm wasn't working.

Fair point, and I didn't mean to be flippant in my response. Since it only tests the buzzer not the sensor, and the sensor also kills the engine revs I guess this is less of a concern. In fact the oil running low is probably a bigger worry - but will now be in habbit of refilling whenever I do the fuel.

Turns out that this isn't what these wires are for afterall.

[Polwart]

Originally Posted by Daniel

the 703 has three wires for connection of a tacho

+12v
Gnd
Signal

I don't remember the colours, it was 5 or more years ago i wired one up

Any marine tacho (QuickSilver (Merc) & Yam for sure) will do so long as it supports the right mode - and that depends on your engine and ignition system. Most marine tachs have a switch which relates to cylinders and other stuff! I think most modern engines work on the same setting but it escapes me.

thanks daniel. Wiring makes sense then.

I don't suppose its as simple as 1 mV per RPM is it! No that way you don't sell as many tachos!

Thanks for the tip on testing the buzzer. Should it buzz at the start (as a test) - or is this only on bigger engines?

Neil