Reading Wiring Diagrams

Home | Dodge Body Builder's Guide contains electrical wiring diagrams for Ram trucks. When a circuit is different for different models, options, etc, the diagram contains abbreviations but they don't define them. One example is NGC. I emailed Dodge and the person got back to me. He said it stands for Next Generation Controller(whatever that means) but said he is not aware of a list of definitions for all abbreviations used in the diagrams. Has anyone came across such a list they are willing to share or provide the website? Thanks