i've rewired both my truck and a Camaro. Good input above. In addition to keeping the diagram handy, i used a highlighter to color over every wire or circuit bundle shown on the diagram as they were completed as I went along. it was printed on an 11" x 17" sheet so it was easy to see and trace the various runs. I also drew in other circuits I added (noting the wire color for reference later in case of problems) for accessories or equipment not supported by the wiring harness used.