If i am using a shift light will it respond to the stock tach? If so, I assume that the light will be off (inaccurate) just like the tach??

 

No the shift light does not use the stock tach. It is wired to the PCM for the correct RPM your engine is at.

 

i needed to know that too, i cant trust my stock tach anymore either.

 

No, it goes off your PCM.

 

most shift lights have their own programming and you hook them up just like you would an auxilliary tach. it will be running off of the ignition control wires to your pcm (im pretty sure). its like the white #10 wire or something on the bottom half of your comp. it wont be reading the mechanical readings of your tach if thats what you mean so it will be accurate on its own.