Finally got a low cost (already had the controller) solution to pull codes from a Deere 4024 I am working on. I got a code SPN 627 FMI 18 that does not have a good reference on an internet search, but it seems to be related to low voltage of something. Either the injection controller or else maybe just the whole battery. There are over 100 occurrences logged, that is as far as I can tell with this tool. Could this be related to the customer letting the battery run low or is it some failure in the injection system? The unit seems to run well besides being a typical Deere smoking pig on heavy load changes. PE4024L001912
Yes, low battery can cause that code. Check your PM.
A neighbor of mine is a retired heavy equipment mechanic. He's warned me a few times that, in his experiences, JD engines are prone to bad grounds and that will certainly cause them to throw codes as well as run less than perfect when a ground is less than perfect. I've experienced just that. Might be a good application for a LOADpro for testing those grounds, if that is the problem.