LED exterior light swap phenomenon

RyanG

True Classic
I recently replaced a bunch of the exterior bulbs with leds. Front and rear indicators, side markers, brake, rears, reverse and plate lights. I also put in a new flasher thing so that the turn signals work correctly. Everything seems to work well. The “phenomenon” that I’ve noticed is that when I turn the key “ignition on”, all of those exterior lights flash on and off just once. Has anyone else experienced this when they went to leds? Is there normal a small surge of current through the lights that is only noticeable with leds because the current is too small to light up the old style filament bulbs. Not sure it’s a problem but just curious.
 

Lowtechprime

True Classic
I replaced every bulb with LED except the GEN light (including headlights). I have not had that issue. It's a 128 sedan though, could be some wiring difference? I assume this is an X?
 

ng_randolph

Bjorn H
I recently replaced a bunch of the exterior bulbs with leds. Front and rear indicators, side markers, brake, rears, reverse and plate lights. I also put in a new flasher thing so that the turn signals work correctly. Everything seems to work well. The “phenomenon” that I’ve noticed is that when I turn the key “ignition on”, all of those exterior lights flash on and off just once. Has anyone else experienced this when they went to leds? Is there normal a small surge of current through the lights that is only noticeable with leds because the current is too small to light up the old style filament bulbs. Not sure it’s a problem but just curious.

LED's respond much, much faster than incandescents, so it is possible that the condition was there before you replaced the bulbs; with incandescent bulbs you just didn't see it. But I have a hard time understanding why this would happen in the first place. Any chance you have an alarm installed?
 

RyanG

True Classic
No alarm that I know of. I’ve had the car since Nov and I’m staring to go through some of the wiring. All the exterior lights were working fine and I just replaced a bunch of them with LEDs. I also replaced the back lights for the gauge cluster and the fiber optic system. There was an aftermarket radio in it that I removed and it looks like the previous owner did some kind of “Brown wire modification” but I haven’t sorted that out entirely.
 

RyanG

True Classic
I'll have to pull the flasher out and see if it goes away. Jefco, do you know if there are flashers that don't do this or is this just something that happens when you put electronic flashers in old systems? Again, don't think its hurting anything. The lights just flash, kind of like a new car when you remotely lock or unlock it.
 

Jefco

Daily Driver
Sorry Ryan, no idea if other flashers do this or not. I got the recommended flasher from superbrightleds.com when I got the bulbs 5 years ago.
My original flasher worked until the very last incandescent bulb was removed from either side.
 

JKIDD

Daily Driver
This is the same on my 86 X as well. I changed all the exterior lights + the 3rd brake & interior door lights. All my lights flash briefly, including my non LED instrument lights. If I turn the key slowly, I can get them to stay on by holding it just before the "ON" position. I can't say for sure it didn't happen before, but I only noticed it after the changeover. Electrical is not my strength, but can this be related to the light power running thru the key switch?
 

Dr.Jeff

True Classic
If I turn the key slowly, I can get them to stay on by holding it just before the "ON" position.
This comment makes me wonder if it has something to do with the "key in ignition" switch....the little contact inside the ignition cylinder that connects to those two white wires on the second little electrical connector. That triggers the seatbelt warning, etc, so the driver knows he has put the key into the ignition. :rolleyes: Try unplugging the little 2-way electrical connector under the steering column (next to the larger 4-way connector that is melted from the brown wire overheating), and see if the issue still happens.
 
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