Tach and speedo issue
 

Wondering if anyone came across this one...

After my FD sat for a few weeks the and the battery drained (should have disconnected it) I charged it up and now my speedo and tach are both inop. Is there a fuse that may have blown that only provides power to those 2 items on the cluster, all other gauges are working properly.

Thanks for the help guys, much appreciated!

This just happened to me a month ago and I just got my speedo/odometer/tach working today. My car was down for over one year and when I went to start it a month ago the tach and odometer and speedo did not work but all of the gauges funtioned properly.

This is quite a common problem and it seems that some people have had luck by disconnecting the positive terminal on the battery for a minute and then reconnecting it. I have no idea why this might work but for me it did not.

The usual cause outside of a wiring problem is that a couple of the capacitors on the speedo go bad. The speedo sends a signal out to the tach so if your speedo goes out you have no tach. You'll have to remove the gauge cluster and visually inspect the capacitors on the speedo circuit board. There is an excellent tutorial on how to do so. Just search for speedo tach problems.

In my case it was not the capacitors that went bad but one of the Zener diodes near the 1000uF capacitor on the speedo circuit. I replaced that diode, which is a 4.7v Zener diode, and the 1000uF capacitor since I was in there already and fired my car up today and now have restored functionality to my speedo/odometer/tach.

Perfect, thanks for the info! I will try and disconnect the positive terminal first, and keep you guys updated on the capacitor/diode situation.

There are dozens of threads about speedometer issues. Please search before posting new threads.

e.g. Here's a thread from just the other day. Speedo Issues?? - RX7Club.com