The fusible link runs from your starter relay, where the positive cable from the battery comes in, up to the middle wiring block on your bulhead connector. Should be the middle harness, top right connector. Follow it from your relay into your wiring harness. They are made to burn out, to save you from a engine bay or dash fire. If you have not replaced it, I would bet thats your problem. You can bypass it, like I mentioned, or rewire a fresh fusible link or fusible wire back into the bulkhead connector, but my issues with these have always been failure at the actual bulkhead connector. I always drill them out and run fresh wire.