Lights stay on

[Waterloo]

Here is the link to all of the Navistar Bodybuilder guides, I would start there. http://bodybuilder.navistar.com/General/Home.Htm

If you need her fixed fast, I would run the truck by the dealer and have them run DiamondLogic on it and see if that can pinpoint the exact issue. They should be able to pinpoint it for you, that will be your fastest route to fixing this issue rather than throwing parts at your truck. The canbus system on these trucks is a real nightmare, even with the schematics.