Tach signal. Is it 12VDC square wave?
 

Hooking up the Haltech F5 and it says to connected it to the negative side of the trailing coil. (Figure that to be the black/white wire on the two prung harness). I installed it on the yellow blue tach signal since I assumed it was 12V square wave output?

Any ideas.

Thanks,
Ian

Would have to be a square wave, yes, but I don't know about the voltage. 12v sounds high for a signal voltage (5v is common for digital (square wave) signals), but I dunno...

Hailers might know, then he could one-up me :)

BTW, when you say black/white wire, you sure it's not black/yellow? Because if it is, that's your POSITIVE wire from the main relay...

hmmm. NOt sure. I would have to go out and look at the car. Its raining and tarped:) I thought it was black with a white strip but your probable right. And another thing your right about the tach being a 0 to 5 volt pulse. No good. I'm going to have to see if I can find the 0-12volt square pulse from the negative side of the coil.

I measured around but saw constant 12vdc only. But I gather the meter is to slow to respond to such a change.

Thanks for your help.

Yeah, a multimeter doesnt have a fast enough trigger rate. Plus a square wave is not a constant DC voltage.

I could drag the o'scope out to the car if I had my FC here at work, but I am driving my buddies FD, and he probably doesnt want me probing around his car..