Electrical Hacker Bait: LED Problem

"Rusty Vandura - www.tinyurl.com/keepoppo" (rustyvandura)
06/20/2020 at 19:59 • Filed to: None

I bought a bunch of LED bulbs for my Crappy Vic because the incandescent bulbs have all but melted all of the sockets in the car’s ten years of life. But here’s the thing: with the LEDs in place, the blinkers tend to blink fast as if there’s a burnt-out bulb. My theory is that the system somehow measures current draw and the LEDs draw significantly less current , so the car thinks there’s a burnout. My idea is to introduce a resistor somewhere on each side, probably in the trunk because easy access, that’s rated at something similar to the draw of the stock bulbs. When the blinkers happen, four elements in the rear on each side and two or three elements on the front happen. So that could be on the order of 2 to 4 amps of draw at 12 volts. Thoughts? Where do you buy a resistor? Is an ohm an ohm?

DISCUSSION (21)

VincentMalamute-Kim > Rusty Vandura - www.tinyurl.com/keepoppo
06/20/2020 at 20:15

The old turn signal circuits use the high current draw of the incandescent bulb to trip a thermal switch (relay?). High current heats up a heat sensitive contact, it opens, no current, bulb off, it cools down, closes contact, current flows again, bulb on, repeat.

Here’s a handy product if you don’t want to do all the calculations:

https://www.superbrightleds.com/moreinfo/flashers-load-resistors/led-light-load-resistor-kit-led-turn-signal-hyper-flash-warning-fix/190/

That is nice since it provides a heat sink for the resistor but you can easily roll your own 50watt, 6 ohm resistors from sources like Digi-Key, Mouser, Ali Express .

Distraxi's idea of perfection is a Jagroen > Rusty Vandura - www.tinyurl.com/keepoppo
06/20/2020 at 20:30

What VM said. I think you can also get aftermarket timer-driven relays that don’t care about resistance, which might be an easier fix.

Tekamul > Rusty Vandura - www.tinyurl.com/keepoppo
06/20/2020 at 20:33

Your assumptions are mostly accurate.

Replace your relays with LED compatible relays. They’re available at most parts stores.

Exage03040 @ opposite-lock.com > Distraxi's idea of perfection is a Jagroen
06/20/2020 at 20:38

This is what I did for the moto when I switched to LED turn signals. Plug and play signal relay for LED lights .

Rusty Vandura - www.tinyurl.com/keepoppo > VincentMalamute-Kim
06/20/2020 at 20:39

Cool! *head swells*

The Vic does one long blink initially then goes fast when there's a filament out.

Rusty Vandura - www.tinyurl.com/keepoppo > VincentMalamute-Kim
06/20/2020 at 20:41

Now, 50 watts and six ohms, did you reference that? I won't melt anything if I go straight to that impedance? Would I put one online on each side?

Rusty Vandura - www.tinyurl.com/keepoppo > VincentMalamute-Kim
06/20/2020 at 20:52

I see that the linked item is 6 ohm/50 watts.

Rusty Vandura - www.tinyurl.com/keepoppo > Exage03040 @ opposite-lock.com
06/20/2020 at 20:54

Interesting. The resistors are $5 a side plus postage. I assume a relay(s) would be more expensive. And Crappy Vic is a hackmobile, so too bad Radio Shack is no more.

Demon-Xanth knows how to operate a street. > Rusty Vandura - www.tinyurl.com/keepoppo
06/20/2020 at 20:57

Parallel. Inline will increase the resistance, not decrease. The other option is to get a relayed blinker module.

https://www.amazon.com/Signal-Flasher-fixes-blinking-Models/dp/B01K3QAMQW

SBA Thanks You For All The Fish > Rusty Vandura - www.tinyurl.com/keepoppo
06/20/2020 at 20:57

Yeah, the old style controllers were thermo-resistive, so if there was insufficient current then the circuit thinks you have a bad bulb. There are LED bulbs which feature a dummy load to trick the controller...

Or, as the others have pointed out, there are new age solid state controllers that don’t care about the low current load.

facw > Rusty Vandura - www.tinyurl.com/keepoppo
06/20/2020 at 20:58

As other’s have said, this is the expected behavior, and provides a very non-intuitive indicator for burnt-out bulbs so ever cars that don’t work this way electronically will sometimes fake it.

Easiest way to deal with it is to replace the turn signal relay with one designed for LEDs.

Victorinoo > Rusty Vandura - www.tinyurl.com/keepoppo
06/20/2020 at 21:20

Why not run factory bulbs? Why led?

Exage03040 @ opposite-lock.com > Rusty Vandura - www.tinyurl.com/keepoppo
06/20/2020 at 21:26

https://www.umnitza.com/led-flasher-for-2006-2011-ford-crown-victoria.html

This one is $20 which is around what they go for (I don’t know how good it is or anything, just a quick google). I hate dickering with wiring so when I did my lights I made everything plug and play.

Rusty Vandura - www.tinyurl.com/keepoppo > Victorinoo
06/20/2020 at 22:04

They’re hot. One of the things I mentioned in my post is that they melt the plastic bulb sockets. LED uses like 1/20th of the power.

Rusty Vandura - www.tinyurl.com/keepoppo > Exage03040 @ opposite-lock.com
06/20/2020 at 22:05

Thank you for looking that up for me. For $20, I’ll try it.

Victorinoo > Rusty Vandura - www.tinyurl.com/keepoppo
06/21/2020 at 08:51

Gotcha, I misread that. What about new bulb sockets and checking the ground connection to make sure you don’t have high resistance that’s increasing the temp? I see this often with volkswagens and bmw. They burn the Sockets bc of poor pin fitment and bad grounds.

Victorinoo > Rusty Vandura - www.tinyurl.com/keepoppo
06/21/2020 at 10:08

Here is a link I found that shows fords are known for faulty wiring increasing resistance and causing burnt sockets:

https://sparkys-answers.com/2008/07/1994-ford-crown-victoria-no-tail-lights.html

Rusty Vandura - www.tinyurl.com/keepoppo > Exage03040 @ opposite-lock.com
06/21/2020 at 13:49

Nine bucks on Amazon. Thanks again for the tip.

Rusty Vandura - www.tinyurl.com/keepoppo > Victorinoo
06/21/2020 at 13:50

I’m hoping that the low-draw LEDs will arrest the decay.

Exage03040 @ opposite-lock.com > Rusty Vandura - www.tinyurl.com/keepoppo
06/21/2020 at 17:17

Right on, should just be a quick swap and good to rock. Let us know how it goes!

Rusty Vandura - www.tinyurl.com/keepoppo > Exage03040 @ opposite-lock.com
06/22/2020 at 00:41

I just assumed that by now, it must be a lot more complicated than that.