Step by step guide for idiots ( idiot, me )
Do the headlights work? They are powered off one of the first branches off the ammeter circuit. Here is a simplified diagram of that part of the wiring
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
Notice that the "light switch" (this is ONLY for headlights) comes off the "welded splice" which is in the black ammeter wire up behind the cluster. This is why I had you check at the alternator. If you have a loose connection at battery post clamp---bad battery cable, bad connection at starter relay "big stud," the fuse link, or the bulkhead connector where the "big red" and 'big black" go through, you may lose power. Also notice the ignition switch is fied power off that splice.
IF the lights work, then pull out the ignition switch connector and get your manual, look up the pin connections for the ignition switch connector. See if you have power going in and out of the switch with the key in "run." That power then goes out through the bulkhead, and feeds underhood loads as I mentioned earlier
You may be losing all power when a load is applied, due to a bad connection. Pick a problem and run it down.
Do the headlights work? They are powered off one of the first branches off the ammeter circuit. Here is a simplified diagram of that part of the wiring
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
Notice that the "light switch" (this is ONLY for headlights) comes off the "welded splice" which is in the black ammeter wire up behind the cluster. This is why I had you check at the alternator. If you have a loose connection at battery post clamp---bad battery cable, bad connection at starter relay "big stud," the fuse link, or the bulkhead connector where the "big red" and 'big black" go through, you may lose power. Also notice the ignition switch is fied power off that splice.
IF the lights work, then pull out the ignition switch connector and get your manual, look up the pin connections for the ignition switch connector. See if you have power going in and out of the switch with the key in "run." That power then goes out through the bulkhead, and feeds underhood loads as I mentioned earlier