[F-127]

Well I don't see too much harm in posting this graph. I borrowed it for the sake of explaination.(images can be a thousand words...those guys from a presentation I went to on visual persuasion at college would be soo proud!) Check out the graph, when your truck is set to high idle at 1100 rpms(or whatever it be), your charging system must be putting out something above 14.01V. I suppose this was done to prevent the glowplugs from seeing to high of a voltage for an extended period of time to prevent burnout. This is from a stock calibration, and I don't think it would have been changed for the tune your using. Hasn't happened to me, but I also don't remember the last time I used the high idle.