What is the electronic doohickey attached to the EVR on a 460 motor? I have no EGR, I am getting code 34 (no EGR opening detected), but I am not sure that the testing procedure I have is correct for this EVR since it is different than all the others I have ever seen. This one has an extra electronic box between the EVR and the plug. I can see it has some diodes and other electronic components covered in epoxy. I can ground the green wire and the EGR will open, and I have already checked continuity between that wire and pin 33 on my ECU and it's good. So I either have a bad EVR or a bad ECU. I have swapped EVRs with another used unit to no effect.

The book I have says the resistence on the EVR should be 20-70 ohms, I have 125 on one and 190 on the other, but I am not sure the figure is correct since it has the extra box on it. What does that box do? And how can I be sure it's not bad?