i've just recently bought a tachometer..its got the 3 gauges inside the tachometer...oil---temp and something else...forgot..but i need help w/ the wiring colors----at the ECU.....i couldn't find a diagram to show the wirings and what they are....i need to get it done asap since its really gonna be bad day 2morrow w/ chilling weathers and nasty snow....all nite if i have to before it gets reallie bad.

I'm running h23 wiring harness.....h22a engine.......need help w/ wiring colors...any help would be greatly appreciated...thanks

 

f-a-q

 

iv'e looked and looked in the *** before i came writing in here.....if u know exactly where..please give me the link then..thanks

 

https://honda-tech.com/zerothread?id=918703

 

does anyone have a good pic of the ECU layout---the one they have there is small..blurry...when you save it in jpeg and zoom in...gets very blurry...can't see anything. email it to xiong0548@fvtc.edu thanks

 

The FAQ had working pictures but I'm not sure now so I sent you the ones I still had.

 

http://www.imagestation.com/picture/...9.jpg.orig.jpg
that other thread also explained how to get this full size pic but it's screwy.

you may need to load the small one first, then add the .orig.jpg

 

this tach comes w/ a oil temp (white), water temp (blue) and oil pressure (Orange) wire--.....i want to install those and have them gauges work too.....would those go directly to the unit in the engine bay or can i wire them up on the ECU wires???

the yellow wire from the tacho goes to the wire for light switch on the vehicle??

 

Not sure if it’s wise to hack into the ecu for your oil temp, water temp and oil pressure. The gauges draw a fair bit of current and the signals going towards the ECU form the sensors (like water temp etc) are specific (in the sense of voltage and amps) so if you place an alternate route for the current to flow its will affect the ECU's ability to correctly read the motors conditions. Say for example some current is lost from the water temp wire then the ecu could interpret it as the engine being cooler than it really is and therefore prevent vtec engagement. That’s my opinion anyway and hence I mount my own sensors for the oil temp/press and water temp. Easy way to ensure the engine runs at its prime.

As for the wires of the tacho:
White connects to the 12v fuse for the dash lights
Red - connects to +v12 fuse (only when key is on, radio, lighter)
Black - ground it to the chassis of the car
Green (tacho) - goes to negative side of coil or in my case (internal coil) it’s on the blue tacho service connector which is in front of the fuse box.

 

Those sensors read off of potential (voltage). Stealing the miniscule amount of current needed to create that same potential over the sensor wires is not going to make a noticeable difference...the resistance of the wiring will make it so that such a small difference in current will not effect voltage much.

 

That is true but in my experience even the slightest change in the path that the current can flow affects the functioning of the parts involved in that circuit. I installed an electrical temp gauge and got the signal from my existing factory temp gauge. My factory temp gauge remained on cold/one bar while only my aftermarket temp gauge was functioning when it was all wired up. This indicated to me that the current in the circuit decreased due to the extra resistance of the additional wire going to the extra sensor. Long story short, by connecting my sensor's wire on the same place as my factory temp gauge's input from the ecu it compromised my factory temp gauges' ability to function correctly. Ohms law applies here as well, if you increase the resistance in the circuit by adding more components (another gauge) in the circuit the result will be a drop in the current, which affects the components functionality.

That’s my experience on the topic anyway and this is why I get additional sensors to prevent my factory system from being altered.