How do you test the tach signal?

[AKimmel]

I've read on hear that people are getting 4 to 5 volts from there tach signal. I tested mine and can only get . 137 volts on DC or AC. I'm wondering if its because its a digital meter. I noticed if I keep breaking contact with the signal wire, I get a little over 3 volts for a split second, but if you hold it on the contact it will settle back to the . 137V. I want to make sure I have a good signal before I spend the money on a tach. Thanks

 

[cerberusiam]

Where are you testing at?



Talking to the guys at Isspro when trouble shooting my tach install the signal produced by the PCM is pretty high freqeuncy and low amplitude. A DVOM is not sensitive enough to read that fluctuation, you would need a scope to see it.



Ditto for the signal from the stock CPS.

 

[AKimmel]

I checked it at the plug under the dash. I read about other people getting voltage there, and it seems like there testing it with something common. My friend who's about to graduate w/ a masters in electrical engineering said I should be able to read it with a multimeter, and you only need a oscope to see the signals shape. But, she even said automotive electronics isn't her specialty, so she could be wrong I guess. I plan on using dikota digitals SGI-8 tach signal interface, so that I can run a common tach. I've talked to Dakota Digital and thay said it would work, but I saw on their instructions that you have to have a least a 1 volt signal and I'm not getting that the way I tested it. I need more info, Thanks