My guess would be: your rad fan probably has a plastic housing and requires a separate ground wire to function. Lots of other parts, ie: radio, heater fan, etc., in the car ground through their respective cases/chassis.
not familiar w/ the harness u got, but I put a 12 circuit harness in my 505" 68 fastback. Then decided to go f.inj.. You will do well to make up ur mind on everything u want before starting the rewire, so it will stay neat and orderly. I found the only thing I had to increase in size (wire wise) was the alternator charging wire on my 1 wire alternator. Sean at EZ, "if he`s still there", is really a smart dude, he can answer any wiring question u have !
