25hp Yamaha 4 stroke cockpit oil light

[simonc2409]

I've a 2003 Yamaha outboard and an Avon Searider 4M with the 703 control box. I want to mount an oil light on the cockpit dashboard and later on a tacho.

I've got all the Yamaha manuals and wiring diagrams for the engine but still can't figure out how to wire in the oil lamp and tacho. There are 4 wires coming from the 703 control box; red, back, yellow and green. The red and black are kind of obvious but what about the yellow and green wires?

Any suggestions please?

[Poly]

off the top of my head the green wire is your tacho signal. I think the yellow is 12V - but only with the engine running? but if you search my previous posts you will find wiring colours... - see here: http://www.rib.net/forum/f36/yamaha-...tml#post367591

[simonc2409]

Thank you for the quick response Poly. I saw your other posts but couldn't find any mention of the oil pressure light.

I was a bit uncertain about the tacho signal as the green wire comes from the rectifier according to the engine circuit diagram, but if it's an unrectified feed from the coil then that would make sense.

The only yellow wires in the engine come from the 'Electrothermal ram' whatever that is?

[Poly]

Originally Posted by simonc2409

Thank you for the quick response Poly. I saw your other posts but couldn't find any mention of the oil pressure light.

I was a bit uncertain about the tacho signal as the green wire comes from the rectifier according to the engine circuit diagram, but if it's an unrectified feed from the coil then that would make sense.

The only yellow wires in the engine come from the 'Electrothermal ram' whatever that is?

I'd guess your 25 HP engine may not have an oil pressure switch? Wiring Color Codes for YAMAHA Outboard Motors.

[Davie]

There is an oil pressure switch on this engine. Find the pink wire it's at the end of it.
Take the power from the yellow at the control box to your light. Run a wire back to the oil pressure switch for your earth return.
Your oil light will now come on when you have low or no oil pressure...
Why not just get the rev counter with the lights that came std with the engine?

[simonc2409]

Thank you Davie, that was the answer I was looking for. I can see the pink wire going to the sounder (figures). Engine didn't come with a tacho, only a spare control unit.

[simsy]

Tacho's on outboards often take the signal from the generator before the rectifier, not the spark system.