Just bot an M35A3. Went to start it to bring it home, flipped on the accessory switch and it buzzed for about a second and went quiet. No power to the gauges, air pressure horn, starter switch. Headlights, heater fan etc work so it is not a battery issue. Previously worked fine. Where can I find a wiring diagram and can anyone help me troubleshoot this problem? I would like to get the truck home!!!!