Hi all: My tach stopped working the other day and I am looking for information on how to troubleshoot it. My rig is a 1991 Gulfstream and I have the 5.9 cummins. The tach uses a mag pickup. I can read about 2Khz at the back of the tach at idle and this increases to about 8Khz at full throttle. I also have the required 12V for instrument power there too. This ratio seems about right to me but would like to confirm this with someone that has more experience. Assuming this is OK then can anyone recommend a good source for a new tachometer. I have not had much luck finding any by the way of the internet. Thanks for any and all help, Roger.