I just about got my engine harness put in (67 camaro w/ small block 350) then ran into a little snag when I got to the engine ground. The ground that I pulled off only had the purple wire connected and if you look at the pic you can see where the yellow wire was just cut off and taped. The new harness has both the purple and yellow wire. Why would the yellow wire be cut off? Should I not attach both the purple and yellow wire?