2001 XJ LED blinkers cause brake lights to flash??

OK so I'm trying to figure this out before I just go back to standard bulbs all around...

I have Sylvania ZEVO 3157 LED bulbs in my rear brake lights and those work great. I also have an LED in my top 3rd brake light which works great.

I also have swapped in the appropriate Relay w/is supposed to be good for both incandescent and LED bulbs.

My problem is when I try and swap in the same ZEVO 3157 LED's into the blinkers (either in the front or the rear)... Here's what happens.

When the parking lights are off... and I flip the blinker on, the opposite side brake light/LED also very lightly flashes in sync w/the turn signal. Turning left... the left blinker blinks and the right brake light blinks... If I have the parking lights on then the brake lights don't flash w/the blinker.

If I leave in the old incandescent bulbs in the blinker location then all the lights work as they should. Is there an easy way to fix this or would I be better off just putting the older style incandescent bulb in the blinker locations? I don't get the hyper-flash issue due to the proper relay being installed.

Any insight is appreciated. I know LED's aren't necessary, but they are much brighter and also have a quicker blink/flash then the old incandescent bulbs do (not talking about the hyper flash here...). I really like the look if it's possible to have on my old '01 XJ.

i would check the grounds. usually its a ground issue when things like this show up. and an led requires a lot less current to illuminate so if a light if looking for ground it will reverse feed the leds.

Had the same problem with my '89 when I swapped to LED bulbs. Seems the LEDs don't have enough resistance to prevent back feeding the circuit. Some people add "load equalizers" (resisters to make the circuit "see" regular bulbs) to stop the unusual behavior, instead I added diodes to prevent the back feed. Resisters defeat the purpose of adding LEDs-lower power consumption, diodes do drop the voltage ever so slightly going to the bulbs but don't increase power consumption, automotive LEDs are not very voltage sensitive typically stable from 6-36 volts, and will prevent the odd behavior of the brake lights. Don't forget to add a solid state flasher to drive the turn signals and flashers.

i didnt have any issues putting led's in my 88. i did swap the flasher to a solid state. still need to look into making a circuit so i can hear the blinker again.

Did you add a diode to the blinker or the brake light? I'm not a genius when it comes to electrical but I can follow directions pretty well... usually. Ha.

I did add in a Novita EP27 Flasher I picked up from Autozone which is supposed to work w/ LED, Incandescent or a combination of both. I don't have the hyper-flash but I do get the brake light blinking w/the turn signal blinking... and it's the opposite side brake light flashing w/the blinker. If it was the blinker and brake light on the same side I'd actually like that and keep it. But it could be confusing to a person behind me seeing my Left turn signal blinking and also my Right brake light blinking in unison.

is it the brake light side lighting or the parking light side? im still inclined to say its a grounding issue. it could be as simple as a dirty connection at a bulb.

lawagoneer said:

Had the same problem with my '89 when I swapped to LED bulbs. Seems the LEDs don't have enough resistance to prevent back feeding the circuit. Some people add "load equalizers" (resisters to make the circuit "see" regular bulbs) to stop the unusual behavior, instead I added diodes to prevent the back feed. Resisters defeat the purpose of adding LEDs-lower power consumption, diodes do drop the voltage ever so slightly going to the bulbs but don't increase power consumption, automotive LEDs are not very voltage sensitive typically stable from 6-36 volts, and will prevent the odd behavior of the brake lights. Don't forget to add a solid state flasher to drive the turn signals and flashers.

Click to expand...

Diode was going to be my suggestion too. total voltage drop across a standard 1 amp diode is .7 volts.

Bad ground shouldn't cause backfeeding.

I added the diode to the feed side of the turn signals. It was over kill but I did it at each light. Diodes are cheap and I had to buy 20 for $2.99 so I used them. xCWolf thanks for stating the voltage drop of 0.7 volts, I just couldn't remember it last night. On 12 volt systems, usually running 13.8-14.6 volts, 0.7 volt drop is nothing. My signals work great now. When I was trouble shooting the problem I had so many issues with the factory wiring in the front I ended up totally rewiring the front signal circuit.

Yeah .7 no different from a weak battery really. I really want to get leds all around ESPECIALLY For my headlights would like that extra power for my sound system lol

xCWolf said:

Yeah .7 no different from a weak battery really. I really want to get leds all around ESPECIALLY For my headlights would like that extra power for my sound system lol

Click to expand...

I have LEDs for everything except my headlights and driving lights. I'm saving up for a good set (Trucklites or something comparable). I did it more for the longevity of the light than the power savings, I have a 160 amp alternator, so power consumption isn't a big issue to me. I like using diodes to protect circuits and use them frequently. Now that they are in and all working I love them. I did the conversion a couple of years ago so my dash lights don't dim which is no big deal to me. My interior lights and floor lights were the biggest improvement for me as I can really see inside the truck now. The signal and brake lights are also brighter but not massively. I do like that I've saved a few operating amps and defiantly love the additional life of the bulbs. Don't waste your money on cheap bulbs, just spend a little more up front for the good ones. I went cheap on my foot well bulbs and had a couple of chips fail pretty quickly on those. Changed out to better bulbs an not problems since. On final thing is that LEDs are polarity sensitive so if the don't work when you plug them in, reverse them.

Bad ground under back bumper maybe

90xj06 said:

is it the brake light side lighting or the parking light side? im still inclined to say its a grounding issue. it could be as simple as a dirty connection at a bulb.

Click to expand...

If I'm understanding your question correctly... on my '01 XJ the parking light and brake light bulb are the same. The configuration for the rear lights on my XJ is Top=Brake/Parking, Middle=Turn, Bottom=Reverse ...

This is good information for me. Can anyone recommend a diode part # and place to pick them up. I did a quick check of A-Zone's website and the only diode I could find was a 'painless wiring diode' and it was $10.99. At that price point I think I'll just swap back in regular bulbs as it would take 4 of those to get the LED's to function properly... 2 front and 2 rear. That get's pricey for simply having LEDs in the blinkers.

Redsnake said:

If I'm understanding your question correctly... on my '01 XJ the parking light and brake light bulb are the same. The configuration for the rear lights on my XJ is Top=Brake/Parking, Middle=Turn, Bottom=Reverse ...

This is good information for me. Can anyone recommend a diode part # and place to pick them up. I did a quick check of A-Zone's website and the only diode I could find was a 'painless wiring diode' and it was $10.99. At that price point I think I'll just swap back in regular bulbs as it would take 4 of those to get the LED's to function properly... 2 front and 2 rear. That get's pricey for simply having LEDs in the blinkers.

Click to expand...

i was wondering what side of the dual filament bulb was lighting. if it was the brake brightness side i would almost 100% say its a grounding issue. if it was the dim parking light side. it could be from bad wiring or grounds at any lighting source.

90xj06 said:

i was wondering what side of the dual filament bulb was lighting. if it was the brake brightness side i would almost 100% say its a grounding issue. if it was the dim parking light side. it could be from bad wiring or grounds at any lighting source.

Click to expand...

More good info... I don't know for sure which was blinking as the bulbs and housing was back assembled when I noticed it doing that. I'll have to do more investigating on my rig and report back if I find out which is which.

These are the diodes I used. https://www.radioshack.com/products/3-amp-400v-diodes?gclid=CPz5gIz_jtICFYOEaQodh00AEg

lawagoneer said:

These are the diodes I used. https://www.radioshack.com/products/3-amp-400v-diodes?gclid=CPz5gIz_jtICFYOEaQodh00AEg

Click to expand...

Thanks! All the Radio Shacks around me have all closed down. I didn't realize you could still get stuff from them online.

Yea only a few brick and mortar stores left. Online is cool. Any electrical supply house can hook you up. Those were the ones I used and had to buy 20 of them so I am pretty much set for life.