Two burned out tachs in one weekend?

The 5 inch Sunpro Tach in my Bel Air quit working for some reason. Checked all of the connections, made sure I had a good ground, and made sure there was a signal from the distributor with my test light. My multimeter was dead so I couldn't check the voltage. After all of this, it still won't do anything. I can't even adjust the shift light, or check where the shift light is set. So then I took the old Suntune tach that was originally in my Bel Air (worked when I put the Sunpro in) and decided to put it in my 1981 Chevy K20. I hooked everything up the right way, and when I start the truck the needle will just flicker, but it stays at 0 when the truck is running. Then when I shut the truck off, the needle will flicker again. I checked all of my connections and the ground with my test light and they were all good. So are both tachs really burned out??

Hard to say, only over voltage will fry stuff and if burned up I would expect no movement from the needle. Two cars, two different tachs all combinations displaying the same results.

Thought about this ZERO ADJUSTMENT AND POINTER POSITION read page two closely of the link below, double check yourself. There are a few adjustments there you should think about taking a look at. Maybe got bumped out of adjustment with all the moving around from car too car just guessing. Seems odd that you could fry two tachs like that without something else going on.

Good luck tell us what you find even if it is operator error, we all make mistakes..

Do you have the installation instructions?

http://www.tradervar.com/All%20Other%20Sun%20Tachs.pdf

I don't have the installation instructions. I did have them when I put the Sunpro in the car, and I labeled all of the wires on the Suntune when I took it out. Everything is hooked up correctly. I'm going to check everything over again tonight and see if I can figure anything else out.

These are the instructions:

http://www.tradervar.com/All%20Other%20Sun%20Tachs.pdf

Okay well I figured out the one in the Chevy K20. I must've had the labels wrong and hooked the coil wire to power, and the power wire to the coil. I didn't even pay attention to the color. So I switched that around and everything works fine now.

On the 66 Bel Air, I redid the connections to the tach. Now I have power to it. The shift light works and everything, but the needle is still stuck at 500 rpm. It doesn't bounce or anything.

If the shift light is working then that tells you the signal is being received, the movement/needle not function could indicate a failure. I would recheck these Cylinder selection set correctly, Mode selection correct?

Good job on what you have done so far.

The cylinder selection is on 8. I even moved the switch back and fourth from 8-6-4-6-8 and it didn't make a difference. I guess it's time to find a new tach? That really sucks since the tach has only been in the car for maybe 200-300 miles.

200-300 miles what's the warranty for it, how long have you had it? But hey 1 out of two working is better then none..

I had it sitting in the package for about a year before I put it in the car which was this past winter. I don't think there was any warranty on it. Guess you can't beat an old tachometer.

Sounds like something that could happen to me, you are now educated and a practitioner of Tach installs, wiring and calibrating, so all is not lost.

:D