My Tach Jumps to Shift Light RPM and Does Not Move With Engine Running?
May 7, 2020
Autogage series tachometers exhibit this behavior when the signal wire (Green) is connected to an improper source, or when it does not recognize the tachometer signal it has been connected to. Be sure to check out our Installation Information section to verify that you are connected to the proper location.
This symptom also occurs when using a tachometer signal generated by a factory PCM or ECU that uses a 5 volt square wave instead of a 12 volt square wave. If this is the case, it may require a tachometer adapter to make your Autogage tachometer operate with your computer, or you may upgrade to an AutoMeter tachometer. Again, make sure you are connected to the proper wire and location at the computer first.