Yea but when you step on the throttle the vacuum goes to 0

 

I think I remember a tach out signal. this will be a square wave. But it might just trip the hour meter.

 

The hour meter needs a constant 2v ( not 12v like I thought earlier ) or higher ( 2v to 27v is ok ) to count up the hours. If that changes anything.

I was wondering myself about the Tach wire. In EV, it is off the "peg" but not much. ICE on, it is a big jump to get to 1000 RPM. ICE is never less than 1000.

So if EV = less than 2v and 1000 RPM = more than 2V we may have a winner.
Ideas?

 

Cant find it in the wiring diagrams, and the tach in the insrument panel is a can bus thing. Still looking. Oil pressure t is still the best IMHO

 

Actually did you measure the oil pressure switch voltage? The voltage will go high with the engine running.

 

I will go out and try right now.

 

MARK- you were correct all along. The oil pressure switch DOES show 12.65v when the engine is running and 0.07v when not running.

This should work as a timer trigger, I think.

I must have had a bad connection or something last time I tried to measure...
If at first you don't succeed, try try again!

How about the wire that drives the tach.
Would that be something over 2v? and under 0.5v when in EV?
It would be a closer option for the tap, but maybe not worth the effort.

So what does the oil pressure switch do anyway?
And what would happen to the car if some-how I interfere with it?
Thanks for all your suggestions.
-John

 

Not for nothing but I believe I suggested the OPS to you first.....

I know, even a stopped clock is right twice a day.

 

You were both right all along!
The first time I tried metering it I screwed up.
I had a bad ground on the volt meter or something.
It is a long way form the dashboard, but it just may work!
Thanks.

 

Here is my finished run time meter.
The clock on the left is for "total run time".
The clock on the right is for "engine run time only".
The toggle switch is to display "lifetime hours" or "trip hours".
The push-button is to reset "trip hours" only.
You cannot reset the lifetime clock.
The orange wire all by itself is the engine on trigger.
-Cost? about $60.
-John