Where on the ignition coil does the tach lead wire hook too? I am assuming it goes to ignition coil. I need help so I can get this hooked up today. Thanks

 

If it is an unfiltered LT1 (late 95 and up you can use the white wire from the ECM to the in dash tach If I remember correctly.

 

But, if the in dash tach is known to be off from actual RPM, then what's the point of using the PCM output for the tach?

 

Its a 94. Anybody know how to do this?

 

The PCM puts out the correct RPM signal - it gets it direct from the Opti. Its the stock tach that indicates incorrectly.

 

Ok, that's good to know! Thanks for the correction!

 

I'm not sure where the tach filter is, but it has to be removed to use the white wire with an after market tach. Not positive on the years either, I just had a freind tell me he thought the 93s were the only year with the filter inline for the factory tach, then again I had another freind tell me it was any LT1 with the dual coild connectors instead of one. I'll have to let someone that knows more tell you that.

 

I read somewhere that it is the white wire on the black coil connector. Does that sound right? Has nobody ever wired a tach in these darn LT1 cars.

 

I wired the one on my LT1 S-10 from the ECMs white wire, It more than likely is the same wire on the coil, it looks so according to the wiring diagram for our cars.

Shoeboxs site has the wiring diagram on it.

 

White wire black connector. (pin 13 or 15, maybe 16 don't remember)

I have a 94 also and an aftermarket tach, hooked up fine with no other
issues, also it's faster that the indash tach and seems to be right on with tunercats rpms.