74 Dart won't start - ignition switch - maybe starter relay?

I got a 74 duster, if after doing the by pass on the reset button on the inner fender, if for some reason the interior lights, radio,cigarette lighter, glovebox light, doesn't work , then that means the interlock module under the dash is bad, its between the radio and glovebox on the wiring harness, you can't just cut it out, it's a light beige plastic box,about 3in wide by 5 in long, they made a green one and an orange one for cars shipped to canada and mexico, those 2 color are plug and play bypass because no seat belt laws were mandatory . I finally removed my underdash harness and found a 75 ,and changed the wiring under the dash, another thing to look at is if under your front seat if the seatbelt buzzer wiring is unplugged, you can rewire it, if you put in new upholstery or seats and unplugged it, it will not start. If for some reason you want the orange or green bypass module under the dash, you can find them on ebay from $150 to $200. I went the route and put the wiring harness from a 75 dart that i bought for $75