What I did for my speedo was, took off the clear "shield" in front of the gauges, and plugged in everything in the back. Then I put the key to the "accessories" position and let the temp gauge and all the other gauges go about their course to the incorrect place. Then I CAREFULLY(make sure not to move the little pin that the needles rest on) removed the needles and put them back in thier correct places. Now if your tach is off you can start the car and do the same thing, normal idle is at about 700 RPM. Hope this helps
