Ignition Switch?

'86 GMC C1500 5.7L V8
So I start my truck up this morning, and it's fine. After being parked in the driveway for the afternoon I try starting it and it
won't even turn over. The seat belt light doesn't come on; the gauges in the dash don't sit up; the radio won't turn on; and there's absolutely nothing (no click or anything) in terms of ignition. WTF? The horn still works, as well as the interior dome/courtesy lights. The headlights come on as well, so it isn't the battery. I checked most of the fuses and they look okay.
Does anyone have an idea what would make all those things fail at once? Is it a bad ignition switch?
Thanks in advance.
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It could be the switch, but I'd be inclined to check both battery cables, both ends. I've had the ground at the chassis end get corroded and do pretty similar to what you describe. There may be 2 grounds (chassis/fender, chassis/engine block) and if the engine block ground to chassis gets corroded, that can be a problem as well.
Sometimes, the ground cable is corroded several inches up inside, under the insulation, from the battery connector. if you bend it and it feels "soft" not stiff, this may be it.
Sometimes an ohm meter (disconnecct ground at battery, measure resistance chassis to the end that goes on the battery) will show the problem. It should be 0.1 or 0.15 ohms, if it's more you have corrosion somewhere.
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Yes! Just looked under the hood and there is a red ground wire back on the firewall that snapped clean in two. Must have been hanging on by a single thread and this afternoon was just its time. Easy fix and thankfully the other wires look sound. Would have taken me days to look there if it hadn't been for your thread, Miller. Thanks man.
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