Hello,
Earlier this year I did put an om603 turbo diesel in my 1981 280GE and didn't hook up the tachometer. I decided to hook up the computer to help it idel cold and to utilize the stock 280(m110) tachometer in my dash. I've hooked everything up to the computer aside from the air flow meter and the altitude adjustment. I figured that the signal coming out of the om603 computer would not be the correct signal for my m110 tach but I tried anyways and doesn't work correctly. When the engine idles the tach reads 7500 rmps, and as soon as I give it any throttle the rpm read drops straight to zero. So my tach reads in the oposite direction and is way to sensitive.

I assume this is due to the signal coming off the ring gear of the om603 and the signal for the m110 came off the crank. So is there a way I can convert the signal from the om603 computer to work on my tack or due I need to figure out a way to get a signal pulse once every revolution and add the electronics for that?

Thanks for your help and suggestions,
Craig