No power electric problem
No, not a relay. The ignition switch is too central to the electrical system. It sends power out to most circuits on the vehicle-those that are designated "hot in accessory, run, start" or some that are only "hot in run or start". Being central, it requires a direct battery source, a "hot at all times" source. Anytime the battery is hooked up, the yellow wire to the ignition switch is a hot wire (actually 2 yellow wires-they splice off before entering the switch or before entering the electrical connector for the switch). The source is Fusible Link M on the starter relay, one of many Fusible Links there, and tied in with the positive battery cable connection. So also, the alternator link is there, so is the headlight switch, the hazard and brake lights Fusible Link, and some others that do supply relays (fuel pump, eec relay, etc.). But Fuse Link M is dedicated to only the ignition switch. If you have no power at the connection to the switch, look at fuse link M. It should have some identifying legend or mark.
Where you saw the sparks, was it at the switch itself or the electrical connector to it? Either way you will have to check. If at the switch, It could be a bad switch, and may have also blew out the fusible link. If at the connector, check if it damaged the connector and is losing contact. Post back with what you find. Good luck.
Apr 18, 2014 |
1989 Ford F 250