Hey all,

Been searching with no luck.
I'm wondering if anybody has the basic specs on the signal for the tachometer. Like the frequency (Range?), amplitude, and duty cycle.
Or maybe constant frequency and varying duty cycle?
I don't have an oscilloscope yet, do you?

I'm thinking about a DIY cruise control.

Thanks

 

Everything you could possibly want to know about the tach signal:
https://www.yotatech.com/forums/f116...gniter-287857/

But don't forget: the tach signal will do you no good for a cruise control. You want a signal proportional to over-the-ground speed, not engine speed. So you want to use the VSS1 signal. Which is already well-conditioned. So have at it.

 

That should do it. Thanks.

Engine RPM with a manual transmission represents a scalar ground speed.
Doesn't matter what the scaling factor is (changes with gear, diff ratio & tires)
As long A RPM is constant, speed is constant. (if you don't step on the clutch)

Auto transmission is of course a different story. My speedo is cable driven.

 

You still have a VSS1; yours is a reed switch in the combination meter (instrument panel). http://personal.utulsa.edu/~nathan-b.../6combinat.pdf Just so you know.

 

I had an aftermarket cruise on my 88 for years, bought it from jc whitney. It worked off of engine speed through tach signal and worked great.

 

On the scope use the ACQUIRE TRACE button and it will do the work for you.