So my question is - what causes the EUP (electronic unit pump) malfunction light to come on? For a couple years now my EMF light comes on intermittently. Mine shows 4 and 3 cylinder . Today i took the two wires off each unit cleaned and replaced to see if that was the issue. When i fired the motor up i was sure it ran better! But then i went and pumped a job and i got the light on once again. It goes out often usually when driving.   My motor runs fine but sometimes i think maybe there is a slight miss when pumping. Only slight. No smoke or power loss. 

sometimes the wiring gets breaks in the coating and will arc out causing a malfunction light , I have had this happen on newer model Macks , 2008 and up

Huh ill check, today it was better.It seems like when i stop and idle for a while it goes on then when i drive it goes off. On a different note: i just got in from the shop i had 5 bolts shear off on my rear axil  hub. I had to drill them out and easy (not so easy) out. Lucky i got them all out and replaced i have a big day tomorrow.

Sheared off! or maybe when the last guy installed the axil he over torched them with a 3/4 impact.