Which pin on the ecu body harness is the tach wire on a S4 N'A that goes to the cluster?
Ive searched and looked through the FSM but no luck.
Also if not to much trouble the oil pressure and temp wires too, if there on there, thanks

 

The attached jpg is looking at the WIRE side of the plug(s).

 

I found this in the fsm. I tried the Yellow/BLue wire in the diagram but nothing, The signal wire is the yellow from the trailing correct?

 

so this one? or is it the other side?

 

I tried it and nothing

 

Yeah. I misread you. You can pick off rpms off the wire in the plug jpg I attached earlier.

BUT you asked about the instrument cluster. It's the yellow/blue like you say.

So what is the problem? No tach signal? There will be no tach signal if the Trail coil plugs are not firing. Also there's black bullet connector at the trail coil that a aftermarket tach can get a rpm signal from.

Oil and water temp signals are not a part of the plugs that go to the ECU.

Looking at the picture, it looks like you have the instructions for some aftermarket gauges laying there. So, if your trying to hook up a aftermarket tach and you don't get it to work from the Y/L wire, it's not the car but something else your not getting right. I'm saying that things like a SAFC use that Y/L wire on the ECU plug to pickoff a rpm signal. Or I can put my digital meter on that wire and get rpm.

 

I'm trying to hook up my stock tach to my haltech e8, i'm trying to find the wire that goes to the cluster.

 

Well, like I say, when a SAFC is installed and you need to pick off the tach signal, they use the wire I pointed out in my first jpg.

Looking into the wire side of that plug, it would be 1X, in the far left, bottom row. Blue/Yellow wire.

The check connector could also be used as the tach signal. Y/L wire. No need to access the back of the instrument panel. The trail check connector is a single wire black bullet connector.


The Trail coil assy needs to be bolted to the chassis and engine running to see a tach signal.

Another place to pickoff a tach signal is at the LEAD coil assy. It has a single bullet connetor that outputs a tach signal.

 

ok, thanks hailers ill give that a try

 

i'm in the same boat! any news? did it work the way he showed you?

 

nope no luck, I think my tacho maybe bad, but if I find it i'll let ya know

 

why not try it directly in back of the cluster,that i know of it's always been the yellow with blue stripe wire.

 

The tach signal originates at the Trail coil assy. If the trail coil assy is not firing, then there will be no signal to the tach. Simple as that.

A workaround is to find the black bullet connector on the LEAD coil assy, and then jumper a wire b/t it and the black bullet connector on the TRAIL coil assy. If the tach is good and the wiring b/t the Trail coil and the tach plug is good, then the tachometer should work. IF the tach now works, you need to find out why the TRAIL coil assy isn't working. Simple as that. Takes maybe ten minutes to do the above.

The trail coils are checked out as shown in the jpg attached. If you have no meter and won't buy one, then farm out the problem to someone else.

If the coils are good, then ohm out the wiring b/t the coil assy and the ECU. If the coils and the wiring is good, then you figure out what to do next.

 

well, in my situation is totally different! the complete og engine harness is pretty much removed! (last owner removed it don't know why!???) the car is running on the microtech lxt-8 and is currently running my single turbo setup. the thing here is that now that the harness has been bypassed the whole cluster is not working besides the oil pressure gauge and back lighting. another thing is that microtech cpu does not provide any leads for the tachs,temp, boost etc...to be hooked up to the cluster..... so theres no way to get a reading of the microtech. any take on this??

 

The harness that has the wires for the injectors, boost sensor etc is the EM harness.

The EM harness has nothing to do with the tach on a series four car.

The stock ECU has nothing to do with the tach, boost sensor output, water temp etc.

Since the oil pressure gauge works, then it follows that there is power for the tach also, but most likely the signal from the tach to the TRAIL coil assy isn't connected OR your not using the stock coil assy's. IF not, then that's why the tach isn't working. If the stock ECU isn't controlling the coil assy's your not going to get a tach signal to...the tachometer.

The wiring is like the attached jpg. From the Front harness on a Y/L wire to the Me harness inside the car. Then the Me harness plugs into the combination meter assy.

If you find that single black bullet connector with the Yellow/Blue (Y/L) wire in the engine bay, then all you do is connect it with the lead or trail coil assy.

I've no idea what a Micrtech does, but if you find the Y/L wire near where the old trail coil assy was, then just connect that wire to to you Microtech coil assy.

There's a jpg attached of a FIRST GENERATION way of attaching a tach wire. Except the color is different.

As far as the water temp goes........it depends on how much of the Front harness is still there. The EM connects to the Front harness in the right front passengers foot well. It's a ORNAGE plug on a series four car. You could run a wire from the water temp sensor to that plug and attach it somehow.