tacho connection yamaha 50hp elec start 05 model

could anyone please help me with the connection of my yamaha analog tacho I have a yamaha 50hp power trim and tilt electric start 2005 model, I was told by a yamaha mechanic that the green wire in the main engine harness is the pulse and the black wire is ground and the yellow wire is 12v power for tacho illumination but I have found that there is no yellow wire in the harness can anyone tell me what is the 12v power source, the colours in the harness are blue,red,brown,black, pink,white and green. does anyone know what wire the blue wire follows into when connected to the harness as it pulled out from the harness and I need to reconnectany help would be appreciated
thanks
Michael

update I connected to the nav lights for illumination and I have 12v power but when the engine is running I am not getting a reading on my tacho I connected to the green wire in the harness and changed to 6P at the back of the tacho but its not reading anyone know what wire I should connect to to get the tacho to read engine revs?
thanks

[boats.net]

The wires for the gauges are at key switch(on 703 side mount control they are next to control cables), there should a short harness with green, yellow, black and red wire with bullet connectors on end of wires.

The wires for the gauges are at key switch(on 703 side mount control they are next to control cables), there should a short harness with green, yellow, black and red wire with bullet connectors on end of wires.

I forgot to tell you that this is a tiller steer model so there are no connections, I have grounded the black wires off the tacho to where the cdi unit is grounded just infront of the starter motor
I just need to find out what wire I can connect to for the pulse is it the 2 green wires coming from the rectifier?

thanks for your help

ok I have grounded the two black wires on the tacho to ground on the engine see picture below black single wire and then I got illumination from nav lights all ok but i cant get a pulse I thought it would be in the green wire in the main harness but no pulse is this correct or is there another problem?

can i get a pulse from any of these wires from the rectifier to the stator? see pic below

thankyou

all done and connected for those that want to hook up a tacho analog to there 50hp yamaha 05 model onwards mine is a tiller elec start trim and tilt then this will work, change to 6P on the back of the tach then connect both black wires together and ground on the engine, then run the tach yellow wire to a 12v power source I went to a spare switch above my nav lght switch and then connect the green tach wire to the green wire on the switch side of the main engine harness the to get illumination I connected the blue wire on the tach to my nav lights and it works perfectlyalso try and use 4mm wire and good sealed connectors.
cheers