Turn signal indicator wiring

[my new 72]

I put Autometer Gauges in the truck a while back, but I never got around to wiring the indicator light back in. I have a wiring diagram that shows that the light blue wire in the loom is for the left signal, and the dark blue is for the right, but are they on an intermittent ground system. I stripped a small section of wire to test them ,and when I put the ground wire to the light blue wire, and the hot wire to a keyed source the light would light up, and when I turned on the turn signal it would flash. How are these supposed to be wired in? I don't mind them not working, but I would like to get them working because I took the extra time to keep the stock arrow cutouts when I modified the inserts to accept the new gauges.