LEDs, Resistors, Flashers - Should I just give up?

[Lance 1992]

I thought we needed another thread on LEDs. I think I've read all of them on this forum, YouTube, and the whole Internet. Everything almost works, but not quite: the side markers aren't working right.

The problem:
When the parking and/or headlights are turned off:
- with the key in the run position, the turn signals and hazards are not visibly operating on the side marker lamps but fine on all other lamps
- with the key in the off position, the hazards are very dim on the side marker lamps but fine on all other lamps. See here:

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The facts:
I do not have a hyper-flash problem.
Electronic, no-load LED flashers were installed for the turn signals and the hazards.
Ground attachments G101, G104, and G105 (the parking and side marker lamp circuit grounds) have all been cleaned and sanded. (They were already very clean.)
All interior and exterior lights other than the headlights have been replaced with LEDs (switchbacks in the four parking lamps) including the dash which of course includes the turn signal/hazard indicators.
Everything works perfectly with incandescent bulbs.
Everything works perfectly when the parking lights and/or headlights are on.
Everything works perfectly if just one LED switchback (in any position) is changed back to an incandescent.
I have tried numerous flashers and switchbacks.

I added resistors. Nothing changed.

What's the problem with the side marker lamps?

Additional information:
I noticed the wires going into one of the parking lamp sockets has been tapped in to. The wires are exposed in a small area.
I sometimes have to turn one of the switchbacks back/counter-clockwise to get it to light, just a millimeter or so after installing it.
One of the side marker lamp sockets seems to have a temperamental connection and I have to adjust/wiggle the bulb to get it to light.
The two issues above are not persistent or consistent.

GIFs of hazards with lights on and off:
Lights on:

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Lights off:

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Note the switchbacks flash a bit brighter when the lights are turned on.

 

[someotherguy]

It's been many years since I solved this issue on my since-sold '94 C2500LD - so I've forgotten some of the specifics.

I put in LED switchback turn signals (from V-LED's, the "regular" style replacements before they came out with all that Triton weird stuff), and corner bulbs (also running LED bulbs in the factory taillight circuit boards).. and the corners wouldn't work correctly. Before this, I had regular LED's and load resistors. I'd since hacked my flasher and removed the resistors. I tried adding the resistors back and everything worked, headlights on or off. It gets tricky making LED's behave when the lighting circuit in these older vehicles simply wasn't made for it.

Flash rate isn't perfect (it's a tiny bit fast) on the hacked turn signal flasher, but is nice and slow on the hazard flasher which is still the OEM thermal unit (in fact you can hear its distinct thunking noise during the slower flashing.)

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Different LED products will net you different results, so that's IMO how it becomes a pain. Like when I ran one brand of LED's in my GMT800 I get more voltage "bleed" back to the turn signal indicators in the mirrors and dash cluster, than when I spent a few more bucks and got different ones.

Richard

 

[Lance 1992]

As Richard says above and Brandon has mentioned in a related post (as well as others), resistors can make things work. I ended up adding a resistor on each side on one of the parking lamp switchbacks on the blue/black wires which is the turn signal/hazard circuit. It didn't work with two resistors on each side (one on each light's turn signal circuit). I don't think you need a resistor to solve the hyper-flash issue, at least I didn't.

For those reading about this in the future, here are some of the variables I tinkered with that made a difference:

Electronic No-Load flashers in both the turn signal and hazard flashers. Oddly enough, depending on some of the variables listed here, I did not always need an electronic, no-load flasher for my hazards - even without a resistor.

LED indicator bulbs in the dash. If you got everything to work without resistors, you may have had incandescent bulbs in the dash. It matters.

Low Battery. All of the testing, even with LEDs would drain the battery to a point where the LEDs would light up but other things would act weird. Like the buzzer and clock and eventually lights that were working perfectly under a set of conditions no longer worked. If that happens top you, make sure to get your battery up at least over 11 volts. Keep a trickle charger on it.

Incandescent bulbs somewhere on the circuit. For example, an incandescent rear bulb could make bulbs in the front work, at least for turn signals and hazards. Even burnt out incandescent bulbs would cause other LEDs to work. This perplexed me when I put two burnt out bulbs in the parking light to make the side marker lights work as I've heard that the filament in those bulbs are used for grounding the side marker bulb.

Resistors. Maybe they work for you, maybe they don't. Maybe you need them, maybe you don't. Two per side was too many for me, none was not enough. I almost had everything working without them. Almost isn't good enough.

Switchbacks with resistors. Didn't work with one, two , three, or four.

Polarity of 194 bulbs. I've seen this mentioned in older posts, but I'm not even sure they still sell polarized 194s. The new ones work wither way and it's easy enough to flip them around. This should not be an issue.

Internal wiring of the switchbacks. I've read somewhere that the side marker lamps may work either for lights or flashing depending on how the ground is routed through the switchback. I'm not sure about that or what it even means. I know if I plug an incandescent 194 into my side markers now with the parking lights one, the two switchbacks will turn from white to amber. Why???

Switch positions. What I mean by this is the various combination of the following four switches: Parking Lights/Head Lights, Hazards, Ignition, and Turn Signals. You can add to his the brake light switch and Reverse light switch. There were a few times when various combinations would cause something not to work. My right brake light would not work sometimes. Be sure to test as many combination of switches as you can, preferably all of them.

That's all I can think of. If you want all LEDs, it is possible - for some of you it may be very easy. For some of us, it's a good deal of trial and error.
I also like all incandescent in a clean, non-cloudy housing!

 

[someotherguy]

A whole ton of variables and trial-and-error. My '94 C2500LD was LED's all the way around, externally, except for the CHMSL because the LED's I initially tried shorted out and caught fire in those sockets! With the hacked OEM flasher to avoid hyperflash, resistors added back in to get the switchbacks working correctly, all was well - with my particular combination of LED's and brands/models/designs of them. Each situation is likely to be different.

Richard

 

[GoToGuy]

Most of the automotive replacement LED's will light with as little as 5 or 10 volts up to 24 volts. So either way they out perform incandescent bulbs / lamps on the high side and low.
And like a switch they are either on or off. No dimming function.

 

[MBRZ71]

Interesting... I've replaced my dash lights with auxito LED blue bulbs and they definitely dim. I'll grant that it's not the dimming range like an incandescent. But it's clear to me at night that it's dimming at least somewhat.

 

[95burban]

I also like all incandescent in a clean, non-cloudy housing!

Brand new incandescent bulbs in new OEM style housings look so nice and warm looking. I like LEDs but they have to go along with the style of the vehicle.

 

[sewlow]

Most of the automotive replacement LED's will light with as little as 5 or 10 volts up to 24 volts. So either way they out perform incandescent bulbs / lamps on the high side and low.
And like a switch they are either on or off. No dimming function.

LED dash lights are dimmable if they have the prefix 'C/K'.
ex. C/K 194.

 

[Lance 1992]

Brand new incandescent bulbs in new OEM style housings look so nice and warm looking. I like LEDs but they have to go along with the style of the vehicle.

At one point during all of this, I noticed that warm glow you mentioned and thought, maybe I don't want LEDs. I seriously considered going back to the old bulbs (that I kept of course). Maybe some day.

 

[GoToGuy]

If they now have figured out a dimming function, great! I know when first was looking my neighbor did the ones I was going to install, they didn't work . But if they work now I'll definitely reconsider getting some.