Hopefully someone knows what kind of signal the tachometer uses. I assume it comes from the EZK, but I do not know the properties of it.

If anyone knows the properties/type of RPM signal to the tachometer for both pre-digidash and digidash cars that would be wonderful.

Cheers!
Carl

 

let me dig up my motec notes. I got the tach working with it years ago.

 

my config just shows an external tach trigger and the wire that goes to the tach in the dash is pin w11. (plug W pin 11) on the fuse panel.

 

Sterling,

Thanks for checking. I found where it comes from and goes to, just need the type (sine wave?, voltage, behavior etc)

Cheers!
Carl

 

I can dig some more. I may have a screen shot from a oscilloscope, if I recall correctly it was a square sine wave. John Speake may be the best person to find out from.

 

It is square.

 

The signal from the EZK is a 12v square wave at 2 x engine rpm. It is fed to pin 1 LH and is the signal that "wakes up" the LH. The same signal
drives the tach and also the kickdown relay (where fitted)

 

Thank you John, and Sterling and Andy

Cheers!
Carl

 

Just a few more followup questions on this topic:

Am I correct in my understanding that the signal FROM the EZK is one way only to the digidash? In other words, 12V square wave going one-way with no return signal sent from digidash TO the EZK?

Second, is the signal from the speed sensor (rpm) processed and altered in the EZK before being sent to the digidash? Or is it exactly the same as read by the EZK?

Finally, with the engine OFF, but ignition ON, should the digidash see any signal on Plug 4, pin 7 (rpm input)? Another way of putting it, the wire from EZK to digidash that feeds RPM should be "dead" unless the engine is cranking or running?

If anyone has a oscilloscope picture of that output, it would be greatly appreciated.

Cheers!
Carl

 

1) It's a one way signal. 2a) yes 2 b) no 3) Dead, no ac signal, maybe a residual dc voltage.

It's easy enough to trace the path from the EZK pin 13 to pin 1 LH, then from pin 1 LH it goes to W11 on the central electric. From there to the KD relay.
Also out to the digi dash - coded "L27" from square C88. Pick up C88 to L27 in that square on the digi dash circuit and you will see the signal fed to the tac and also the diagnostic socket.

 

Thank you John!

I know I am pushing my luck, but as I don't have a running setup to test, and it is a bit of theoretical programming application at this stage, what would a "normal" reading be at idle and at let's say 3000 RPM?

Again, thank you!
Carl