just put in a tach w/ a shift light. works fine, but now my truck idles way too high or it goes up to 3 grand. what is going on?
can anyone help?

 

well i am afraid i do not have to intellegent of a answer for you ,but it sounds like you taped into the wrong wire better disconnect it and go back to basics call the mfg of the tacometer ,ask about your truck or get a wiring diagram to find out where the tac signal can vbe picked up . i was never able to find out were it was on my 95 2.8 s-10 ,good luck