60A fuse blowing

[Fuddyduddy1952]

Yeah, I know you know your stuff, Fuddy! The guy I replaced at my prior job actually started life as a TV repairman in the 1950's, and his trouble-shooting skills as a result of that history were way better than mine.

But I just thought of one possible trouble with the lightbulb method, here. If the plug is only shorting out when it gets hot, you'll need to be sure your bulb allows enough current flow to get the plug to that state. A bulb rated 450 watts at 12VDC is going to limit the circuit to 37 amps or less, and when figured in series with a 1 ohm plug, you're looking at knocking plug current down something like 25%. That's probably fine when testing just one plug at a time, but you'd want a much larger bulb for testing them in groups.

I was using a quick example. I could parallel two 450 watt bulbs, or combination of bulbs for different currents.
That 60A circuit goes lots of places. Unplugging glow plugs may be the key...then again may have one chasing their tail. That's why I'd put an ammeter on that line, turn key with glow plugs unplugged seeing what current draw is. If it's, say, 40 amps fuse won't blow but plugging in glowplugs is the straw that breaks camel's back...it's not a glow plug problem but somewhere else.
That's the "joy" of troubleshooting. I've seen so many things defy logic, physics, electronics...seeming impossible. That's why I resorted to unorthodox methods, light bulbs, heat/freeze, vibration, subbing in a 2 prong flasher for fuse, subbing a variable supply for power source (battery), IR thermometer, to say nothing of the last resort smoke test.
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