Alright folk I have a question that hopefully someone might be able to shed some light on. Basically I have a om617 engine out of a 300sd california emission package that I have swapped into my 1984 Jeep Cj7.

The issue I am having is that I need to get a tachometer signal to my EGR control module so that I can retain the functionality of the EGR system. The reason I need this system operational is because I live in California and in order to get my jeep refereed it must have all the equipment present and working. As soon as it gets refereed I will be removing all of the EGR garbage but until then it has to work enough to pass the testing.

Alright here's where my problem comes in. I no longer have the mercedes transmission adapter plate or flywheel because I'm using a adapter plate from mercedes4x4.com to mate the 617 to my jeep automatic transmission. I have everything for the EGR control wired up and even have the vr sensor that goes to it but no way to use it in the way the factory intended.

What I'm try to determine is what the vr sensor was reading originally, was it the teeth on the ring gear? In that case will it read the teeth on my jeep ring gear and function correctly? I know there is a rpm sensor on the harmonic balancer as well for diagnostic purposes from what I understand and give a different signal from what is required for the EGR control. Is there a way to run a modified tach amp to give the correct reading. Or perhaps there may be a way for a product like the dakota digital tach to produce a signal that would be compatible.

I've been searching the forums for hours and can't seem to come up with any solution for my specific issue. Any help would be greatly appreciated as I'm at a loss and this is the only thing that's holding me back from getting my jeep refereed and being able to get it out on the road and enjoying it.