LED Headlights randomly going out

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rmel
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Re: LED Headlights randomly going out

Post by rmel »

Hmm, now that's interesting. Are yours Trucklite LED's as we?
And when did you install them, how long after the install did they
start to go goofy on you.

Just thinking maybe there was a bad run out of the factory, these
headlights do use an internal converter to drive the LED array
essentially a Voltage to Current converter. It's not just a resistor
in series with the LED.
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Jimm391730
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Re: LED Headlights randomly going out

Post by Jimm391730 »

Of all the things that could cause an LED headlight to "turn off" randomly, only truck wiring issues (power, connections, switches, etc.) would cause both headlights to turn off and on at the same time. And I have also found out that many of the lighting circuits connect the power lead to ground when the light is supposed to be off; unlike most car wiring that just allow the power lead to go "open circuit". At least I know for certain that my Swiss 712W taillight wiring is such that the power leads switch over to a ground connection when the bulb is not illuminated.

It is VERY difficult to find the problem when the headlights are working as they should. I might suggest that you connect an additional wire from the low beam output terminal of the high/low headlight relay and bring that wire out to a point where you can monitor it with a meter and see if that voltage falls when the lights go out. From that point to the headlights are just some wire, perhaps one or two connectors (and perhaps circuit breakers). Have you tried resetting the circuit breakers (assuming you have a Swiss setup)? But I thought the Swiss used separate breakers for each headlight so that what you are experiencing (both going out simultaneously) does not happen.

And while the LED headlights use less power than "normal" bulbs, they still draw a significant amount of current: common 55W incandescent bulbs draw 1.96A at 28V; IIRC the LED Truck lites that I have are 36W that draw 1.29 amps at 28V (from memory, I haven't measured them). So I wouldn't expect that the relay contact resistance to suddenly be a problem.

I do believe the Truck Lite LED headlights to be polarity insensitive, meaning that can be driven with the opposite polarity ("positive ground"). This can happen when points that are expected to be tied to "chassis ground" are not really connected as good as they should be. This might be part of the reason they flash with the turn signals - could be a missing ground, somewhere.
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Texas710
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Re: LED Headlights randomly going out

Post by Texas710 »

Missing ground, or possibly a corroded grounding point. Might look sturdy, but may need to be cleaned/sanded back to bare metal...
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Re: LED Headlights randomly going out

Post by nicholastanguma »

As usual the lads on this forum are chock full of tremendously helpful tech info. I thought I knew about LEDs--turns out I hardly knew what I thought I knew.

So if a Pinz wiring loom was completely new front to back (as in a complete truck restoration), from relays to breaker box, is there any foreseeable reason new LEDs would have this weird off-then-on idiosyncrasy? Seems to me when everything is brand new then all the components will play nice with one another, assuming no component suffers a manufacturer's defect.
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Re: LED Headlights randomly going out

Post by krick3tt »

When I installed LED lighting on my Mog the current draw of the LED was not enough to cause the flasher to work so I tied them in with the standard lights...same thing on the pinz. I am wondering if the current draw for LED headlights works the same way except there is no standard lighting to tie them into. Perhaps the relay type that the other military vehicles that are 24V will work with them. Most are used by Hummers and their systems are also 24V. Just speculating as I do know very little about LED systems.
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Re: LED Headlights randomly going out

Post by EmbarkChief »

Well tomorrow I'm supposed to be getting my new headlight relay in. I'm keeping my fingers crossed this corrects the problem. If that's not it then I'm going to start researching all the grounding points and see if I can find anything suspect. I do like the "monitoring wire" suggested above.
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Jimm391730
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Re: LED Headlights randomly going out

Post by Jimm391730 »

So if a Pinz wiring loom was completely new front to back (as in a complete truck restoration), from relays to breaker box, is there any foreseeable reason new LEDs would have this weird off-then-on idiosyncrasy?
I replaced the stock headlights and reflectors with the older style of Trucklite LED headlights with no conversion issues at all; haven't had to do anything about them for the years that I've had them. So maybe my wiring was equivalent to "completely new" despite being the same as what it was from the Swiss. This just points out that there must be something wrong with your wiring, somewhere.
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Haf-e
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Re: LED Headlights randomly going out

Post by Haf-e »

Are we talking about the original "9 LED" generation 1 trucklite LEDs or the newer "reflector" type generation 2 trucklites LEDs?

I suppose one possible explanation is that maybe the 24v is exceeding the operating limit and they are shutting off to protect themselves? Not sure why they would work when the blinkers are on except perhaps the additional voltage drop of the blinkers draw is resulting in the applied voltage at the headlights being just below the operating limit. This also might explain why it only occurs when driving compared to when just idling - the voltage would be higher with the engine running at higher RPMs.

So in addition to having the indicators for power at the lamps you should also watch the voltage level as well.
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Jimm391730
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Re: LED Headlights randomly going out

Post by Jimm391730 »

I have the Gen 1 "nine LED" headlights.

I also thought about the headlights overheating, or shutting down from over/under power, but I would not expect them to be tripping at exactly the same time...
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Haf-e
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Re: LED Headlights randomly going out

Post by Haf-e »

If it was an issue with the voltage regulator allowing the voltage to suddenly jump up then it would be possible for them to trip off at about the same time...

Still hard to explain why the blinkers make them flash though...
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Jimm391730
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Re: LED Headlights randomly going out

Post by Jimm391730 »

Yup, it's one of those electrical mysteries (until it eventually gets resolved).
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Re: LED Headlights randomly going out

Post by EmbarkChief »

I have the Gen 2 version with the reflector. Tonight I put in the new headlight relay. They still shut down on me but only for about 5 seconds. In fact they did not drop at exactly the same time. Maybe 1/2 a second apart. At this point I think the volt meter is the way to go. Should tell me if they are getting too much or not enough power.
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loyalp
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Re: LED Headlights randomly going out

Post by loyalp »

My similar issue added a new behavior today. Circuit Breaker #5 popped when I switched the headlights on.

So, I just unplugged the headlights altogether from the connector inside the housing.
Checked the wiring and everything still looks fine with no insulator damage or anything.
Turned on the headlights and *pop*, #5 still blew.

What does this tell me guys, that my relay has gone out?
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rmel
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Re: LED Headlights randomly going out

Post by rmel »

Short, not likely the innards of the relay, not impossible, but more likely in your dash or near the relay -- Ohm it out.

I'm curious what the findings were form the original posting -- resolved or still a mystery?
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Re: LED Headlights randomly going out

Post by EmbarkChief »

I'm starting to lean towards over voltage. Last weekend the lights went out but when I pulled over they came back on, once I brought the RPM's up to get going again they shut off. This repeated itself over and over again. Once the RPM's came down to idle the lights would come back on. Also, if I hit the hazards the lights would come on with them. Maybe the current drain from the hazards was enough to lower the voltage to a safe amount?
-1972 710M
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