My 1996 Sierra 3500 has an electrical problem that I'm hoping someone can help me with. The engine (gas 454) will crank but will not start. While I was checking fuses, I found that none of the fuses that the Haynes manual says are "hot in run" had voltage to them with the ignition switch in the on (run) position. But the manual doesn't show any of the wiring going to the "hot in run" circuit. Does anyone know if there is a relay or circuit, or if it's just the ignition switch that powers the circuit. Thanks.