How did my high beams kill my ignition? Options

[87m491]

After doing some bottom side work on my car last weekend (on ramps), and some dash bulb replacements, I went back topside to drive off the ramps (12 hours later) and absolutely no signs of life when ignition key is turned. No generator light, no oil light nada and of course no cranking. No fuses were blown. While the ignition switch hadn't exhibited symptoms of failing I figured I'd swap it out with a spare I had.

I swapped in the spare today. A bit of PITA so I went down an electrical check list before fully buttoning it up. Key on, dash lights check (generator and oil pressure, still stock incandescent bulbs) . Cranked over and instant start, check.

Installed the directional and wiper switch stalk so I can check the functioning turn signals, check. All the illumination LEDs I installed in the gauges this week, check. Running lights, check. Headlights up and check. High beams to check high beam LED, saw the high beam indicator light, heard a relay, click, momentary check, then the dash went dark!
Again, no fuses blown.

Now I am back to the symptoms that led me to think it was the ignition switch. No lights at all on the dash with key on and of course no cranking. Hazards work, 1st position headlight switch items, gauge illumination works, 2nd position headlights do not and fogs do not.

Data point, all of these items worked before the day before my first "dead electrical' experience last weekend. All wiring that I know of is stock.

Looks like 'll be getting friendly with my multimeter once the coming storm passes through the northeast.

Ideas BTDTs welcome.

[Dave_Darling]

DO NOT REPLACE THE ALTERNATOR WARNING BULB WITH LED.

The charging system relies on the resistance of the incandescent bulb to "jump start" it. Plus the light is supposed to illuminate with current running through it either direction; a diode is effectively a one-way valve for electricity and an LED is still a diode.

--DD

[87m491]

No worries, Gen light is old school. I swapped the directional indicator back to incandescent as well. That cured the always on symptom. As I suspected some small amount of voltage was backfeeding the LED and caused the ghosting. It doesn't take much.

The high beam indicator is not getting power so I'll swap in a new Spoke LED friendly relay as I move to LED external bulbs to go with my Brad M rebuilt engine compartment fuse block and it should be fairly straight forward to figure out. Wish I had a concrete "reason and fix" for the original condition but all seems well and on to the next item on the squawk list.
Thanks all for the help.

DO NOT REPLACE THE ALTERNATOR WARNING BULB WITH LED.

The charging system relies on the resistance of the incandescent bulb to "jump start" it. Plus the light is supposed to illuminate with current running through it either direction; a diode is effectively a one-way valve for electricity and an LED is still a diode.

--DD