When I dove into my dash to replace the dash lights, I quickly found that the electrical system was a 50 year old mish mash of twisted connections and electrical tape. As an electrical engineer, I could not live with this and so I decided to upgrade most all of the wiring. For the main harness, I selected the 1966 UNDER-DASH HARNESS W/ PREMIUM FUSE BOX AND RELAYS from CJ Pony Parts with blade fuses. To my chagrin, when I opened the box there was NO CIRCUIT DIAGRAM. After several queries to CJ’s customer service with no results of value, I called Scott Drake, the manufacturer, directly to enquire about a circuit diagram. Scott wasn’t available but one of his employees told me that there was no specific diagram for this harness but that the classic diagram would work ok - for the small price of $12.95.

I figured I could easily find a circuit diagram on line so I asked Google to find one for me. Google came through and I found a number of black and white diagrams but no color. So I decided to fix the problem myself. First I took an old overall b&w schematic that was divided into two pages. I “welded” them together and imported the combined jpeg into AutoCad. I spent most of a day developing a couple of lisp routines, one to draw multicolored lines and another to label them with the Ford numeric legend. I then spent another couple of days digitizing the schematic. After realizing that the schematic I had did not agree with the earlier versions, I spent another day truing up the overall schematic.

I then took the copy of the classic wiring diagram, the new harness and a circuit tester and had at it. While the classic diagram is close, there are a couple of additional relays and a few subtle but significant changes in the wire colors. So much for Scott’s advice. (I know a real wiring diagram exists somewhere because the harness could not be made without it.) When I was done, I had a complete set of colorized wiring diagrams which I now share with the world. Just click the link below and download a pdf file with all of the necessary drawings.

NOTE: If you have downloaded earlier versions of the 64-66 diagrams, I have spent some time updating and correcting them. This includes revising the linetypes and colors to make them more readable both on screen and printed.

I have added 67-72 diagrams. However, only the 67 and 68 diagrams have the supporting detail drawings. If these exist for the other years, if you send them to me, I will gladly colorize them and add them to the downloadables. Also, beginning with the 69 schematics, many of the line colors are not labeled. If someone will send me the correct colors, I will correct those drawings.  If you wish to download the single schematic drawing, you can right click the image and save it to your computer.

You may also notice that I have mirrored the original schematic diagonally so that the headlights are on the left and the starter relay is at the top. I found it annoying when I was flipping between the detail sheets and the schematic that they were not oriented the same. I hope you agree with me.

If you have any questions or suggestions, you can contact me with the Contact Me button at the bottom of the page.