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LED brake light issue

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Old Jun 27, 2018 | 12:18 PM
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Default LED brake light issue

I'm having trouble with the LED brake lights on my 68. The LED lights include the lens, and are not just LED bulbs. Three of the four lights stay on when the car is off. They are very dim, and appear to be off when outside. You can only really tell when it is dark in my garage. The drivers side outer light is the only one that turns off correctly. I recently replaced the rear harness, do you think this could be a ground issue?

Any help is appreciated?
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Old Jun 27, 2018 | 06:42 PM
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Originally Posted by Kyzarsoza
I'm having trouble with the LED brake lights on my 68. The LED lights include the lens, and are not just LED bulbs. Three of the four lights stay on when the car is off. They are very dim, and appear to be off when outside. You can only really tell when it is dark in my garage. The drivers side outer light is the only one that turns off correctly. I recently replaced the rear harness, do you think this could be a ground issue?

Any help is appreciated?
Did you install a led turn signal relay?
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Old Jun 27, 2018 | 10:28 PM
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Yes I did, I am having trouble with my emergency flashers though. Get solid lights on dash. Think they could be related?

I checked again tonight and when I press brake all 4 fully light up like they are supposed to.
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Old Jun 28, 2018 | 06:48 AM
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Originally Posted by Kyzarsoza
Yes I did, I am having trouble with my emergency flashers though. Get solid lights on dash. Think they could be related?

I checked again tonight and when I press brake all 4 fully light up like they are supposed to.


The hazards use a different flasher relay that is attached to the fuse panel.. So you may need to get a led relay for that.
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Old Jun 28, 2018 | 09:58 AM
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Originally Posted by The Punisher
The hazards use a different flasher relay that is attached to the fuse panel.. So you may need to get a led relay for that.
I replaced them both with LED capable relays. I did go cheap on them. I think they were like 8.00 a piece at auto zone. Maybe the flasher one is defective.
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Old Jun 28, 2018 | 10:18 AM
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Originally Posted by Kyzarsoza
I replaced them both with LED capable relays. I did go cheap on them. I think they were like 8.00 a piece at auto zone. Maybe the flasher one is defective.


Did the flasher relays have a ground wire attached?
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Old Jun 28, 2018 | 10:48 AM
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Originally Posted by The Punisher
Did the flasher relays have a ground wire attached?
No, they were just the two pin type that plug into the original slots. No ground wire.
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Old Jun 28, 2018 | 01:06 PM
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you may have to use one like this
https://www.summitracing.com/parts/u...iABEgKZafD_BwE
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Old Jun 28, 2018 | 03:57 PM
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Originally Posted by The Punisher
That's the one. Note the included (flimsy) pin reversing base. In my 79, I needed the base in my turn signal circuit, but not in my hazards. I tried all combinations first.
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Old Jun 28, 2018 | 04:11 PM
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Think that could anything to do with my brake lights staying on, or just fix flasher issue?
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Old Jun 28, 2018 | 09:20 PM
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The old fashioned flasher is just a bimetal switch, passes current, heats up, and completely shuts off any current flow, over and over. That's the noise you hear when the "blinkers" are on. You might check the impedance of your new flashers (in both directions) which probably have some sort of active semiconductor switch (guessing). Why there's any voltage on the source side with everything supposedly off is another question but I've many times discovered that things that should be 0 volts have some residual voltage on them. And that is leaking to the LED's.

I also remember there being two kinds of flashers but the details are now vague in memory. Got mine from SuperBright. I think I ordered both kinds because .... well that should be obvious.

Last edited by ignatz; Jun 29, 2018 at 11:59 AM.
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Old Jun 28, 2018 | 09:54 PM
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Most times I've seen things like this happen, it's been a bad ground and power was back feeding from somewhere else like the interior lites that have power to them all the time. The headlight switch, the security system, the clock and the ignition switch all have power to them all the time.

Disconnect the ground to all the taillights and then hook the positive from your voltmeter to the ground wire and the negative to the frame. If it shows any voltage, you have a ground problem. Now check each positive wire to the taillights. If they have current, then it's bleeding off from somewhere. You just have to track it down.

Mike
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