Yamaha TRX850 Enthusiasts Forum

I have bought an aftermarket digital tacho/speedo. I have everything hooked up except the tacho. Cannot figure out for the life of me how to hook it up. So.
1. What do the 3 wires going to the tacho do?
2. Is there a single wire I can tap the tacho into?
3. I have the ignitech ignition box, is there a wire exiting the box that I can wire the tacho directly into?
4. Bonus question, what do the 3 wires to the temp gauge do?

I am running Mikuni carbs with the tps enabled.

TACO....It's the yellow/black on the main loom and then changes to grey on the actual std trx dash loom that plugs into the main loom.

Neutral light is Blue( main loom ) and sky blue on the trx dash loom.

High beam Is Yellow on the main loom. I don't have it listed for the trx dash loom..
Right indicator is green to dark green on dash loom
Left indicator is brown to chocolate on the dash loom.

Main loom...
RED is 12 v power from battery ( continual power to allow for clock/ standby on the digital dash)
BLACK is earth
BROWN/BLUE is ignition

All info is from the manual wiring diagrams and correlates to the digital dash I set up. it has its own dash loom colour code which is a Koso and allfunctions as normal..( I haven't listed the Koso dash wiring just the original Trx loom and dash loom above)
The aftermarket dash should have come with its own colour code/diagram so you should be able to match it from the above info.

Extra info handy to know...

The ignition switch itself has 4 wires.
2 heavier 15 amp wires
RED......12v power IN from the loom.
BROWN/blue which is power OUT. to the loom.

The 2 thinner 10 amp wires are...
BLUE/yellow... Side stand/ clutch cut out switches.
BLUE/black to the igniter (ECU)
When the ignition is turned off it DISCONNECTS the main power in/out.
But it CONNECTS the side stand switch/clutch switchs to the ECU which means if someone chooses to try to Hotwire the bike , by just joining the power in/ out you have no spark due to the cut out wires killing spark at the ECU.

Cool cheers Cobba.
I have the speedo, indicators, high beam & neutral all working. Just need to wire up the tacho. So will try hooking up the grey lead.
Also what are the 3 lead colours going to the temp gauge ?

Both the tacho and temp gauge have Brown for +12v and Black for 0v
The sense wire for the tacho is Grey at the rear of the dash which changes to Yellow/Black in the main loom and runs back to the ECU connector under the seat.
The sense wire for the temp gauge is Green/Red all the way from the dash through to the sensor on top of the engine.
All of this is shown in the TRX manual, which you can get from the Download section of this site.

There is a Tacho output on the TCIP4 ECU, Pin 15, Green/Yellow wire.
You can get the TCIP4 user manual directly from the Ignitech site, it has wiring diagrams and full descriptions.

Cheers, Thanks dicky

The wiring diagram is on the disc supplied with ignition so just open the manual downloaded on the disc if you choose to run a wire directly to the ECU.
Bit pointless though as its already Inplace on the multipin outlet and adaptor loom supplied with the prog ignition. It already runs up to the dash via the original loom.

Thanks for confirming the other wiring info Dicky. good man
I'll jot them down on my notes... .

I scanned the 8 wiring diagrams for the ignition, lighting, charging etc, onto my printer, to make it easier to read the fine print for colour codes on the wires, I formatted the printer to print 1 page into 4 segments.
Sticky taped the 4 pages together so the original scanned A4 page is now 4 times a big ( like butchers paper size) and no need for my glasses and magnifying glass to follow the lines and read the tiny codes.

Well I have tried hooking the tacho up both to the loom & also direct to the ignition & still nothing.
I have a horrible feeling that the tacho may be faulty & because I waited so long to fit & test it I can't get a refund through paypal >:(

Is there a quick way to bench test a digital tacho input?

This is infuriating as I can't make any headway fitting the new headlight etc until the standard gauges are removed & as this is my only vehicle I need to get this sorted aarrrgh

What tacho do you have?
Cobba has a Koso, I have and Acewell, others have even more exotic versions.
Maybe we can help if you give us some more info.

No brand name :p
Yea it's a cheapie, part of the reason I need to figure out if it is faulty or if has something to do with the way I am wiring it.

http://www.aliexpress.com/item/Universa ... 03899.html

Not where I bought it but shows the wiring code

If you paid anywhere near what is shown on that ebay page then you are a brave man.
I paid ten times that for my Acewell, but it works
I hope it came with better instruction that are shown on the ebay page.
From what I can see Tacho sense wire is Violet/Black, Speedo sense wire is White/Black
All you should need to do is connect this to the Grey wire that connects to the original dash, or to the Yellow/Black wire on the main loom connector, then start the engine.
I assume that other functions of this dash work and that the original tacho was working?
Do you have a multimeter to test some voltages?

Fault finding...
Connect power to the new dash unit.
Connect a wire to the RPM terminal and then tap it repeatedly on to the 12v feed to create some pulse input to the unit.
3 taps per second is equal to 180 RPM, so you should be able to get something on the display.

I read the
Black. wire taco
Red wire power +
Green/black wire earth -

Violet/black wire speedo

Obviously it only draws 1 power from ignition on position which differs from the Koso.

The Koso dash has a 1st power feed from the battery and keeps power to the dash 24/7 for the clock.
2nd it has an ignition power feed for once the bike is turned on that powers all the functions.(speedo/taco etc)

Ahh, young grasshopper, I have better Zen than you.
Searching the net for the same digital speedo/tacho reveals a much better quality diagram that clearly shows RPM as Violet/Black and Speed as White/Black.
Only deathtoll will show which is the true Zen.

Alternatively, tapping any of the wires to +12v should show something happening on the dial, so you could just go with the old trial and error method until you get it working.

Bit like toilet paper hey Dicky.. swipe up or swipe down and all depends on the sex..

Mate, I've been living in HK for 8 years.
Sideways is the only way!