Bench testing a Tach??

[67chevemall]

Hey I have my tach on the bench to see why it stopped working.

Does anybody have a method to this?

It is a OEM one I bought on the board from Wes.

My other ? is does the whole instrument cluster need to be grounded?

Cheers

[davepl]

You could no doubt make some frequency generator, but wouldn't it be easier to just walk it over to any other vehicle you have and hook up the tach signal and power line to it under the hood? Then you could also compare it to the in-dash tach of that vehicle (if it has one).

Should be trivial if you have anything with HEI or a coil. If you're lucky enough to have a Mercedes V12 BiTurbo, you're on your own, we could never find a tach signal on the dyno! But an older vehicle should be ok.

[JimKshortstep4x4]

Thje dash housing should be grounded as the tach gets its ground from the instrument housing. I would check to make sure the power wire and the wire from the distributor are connected and that you have power to the tach. Tachs seem to hold up well so I would look for something outside of the tach first.

Checking with an ohm meter does not seem to work as the readings from the tach are all open or close to being open. If you decide the tach is bad then sending it to someone in the business is a good option.

Jim

[67chevemall]

Thanks guys. My bezel is wood so I am thinking I just need a ground. My power wire is good and so is the dizzy wire. Just changing the glass on the cluster and I'll try it all out.