This has been updated to include both the tachometer and non-tach cars.This may be more detail than you need, but it is sure to have information you can't get elsewhere. 1. It identifies all the wires coming into the plug for the flex connector, what they do, and how to test them. 2. How the Instrument Voltage Regulator works and how to test it. 3. How the gauges work, several ways to test them, and a detailed method to adjust or calibrate them. 4. How to test each component-