Exterior LED upgrade fail

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Burban1998

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Last night I installed LED switchbacks up front (White DRL with yellow turn), initally when I put them in, the driver's side switchback worked no problem but the passenger side did not (it just stayed amber). I went ahead and threw in a set of tail light bulbs, but realized I didn't order enough of them so I had one hallogen in the top position and the LED in the lower.

When I came back to the front, they now are both amber, and do not switch back to white at all.
The turn signals, brake lights and running lights work wonderfully with the headlights in the off position, but with the headlights on they don't.

I will reply to this with pictures and part numbers, so far I've tried the factory flasher relay (didn't work AT ALL), a part number WMFLL004-3P (turn signals worked with lights off but not with the lights on) and a EFL6 (sped up the flash a bit and the hazards work but still no dice on the headlight position)
Here’a the YouTube video I got my parts list/info from. I’ve only got the one flasher relay. Can’t find the 2nd one he references.
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I think I just need the correct flasher relay but I'm at my wit's end lol
 

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JOHNGAAA1

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You definitely need the led flasher if you do not change the assemblies. Some of the plug and play light assemblies come with the led box which you mount with 2 face tape behind the assemblies.
 

df2x4

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Are you using the factory tail light housings with the circuit boards? If so, are you running SRCK compatible LEDs in the middle sockets on both sides? If you aren't, you should be. Not sure if that would cause these specific problems but I know you need LEDs that are listed as "SRCK compatible" in those two sockets for proper operation if you're using the factory housings. Like these:

https://www.superbrightleds.com/3156-3157-ck-led-bulb-dual-function-27-smd-led-tower-wedge-base

The listing for the LEDs needs to say "SRCK compatible," you can't assume they are just by how they look. It's a difference in how the sockets are wired.
 

Burban1998

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Are you using the factory tail light housings with the circuit boards? If so, are you running SRCK compatible LEDs in the middle sockets on both sides? If you aren't, you should be. Not sure if that would cause these specific problems but I know you need LEDs that are listed as "SRCK compatible" in those two sockets for proper operation if you're using the factory housings. Like these:

https://www.superbrightleds.com/3156-3157-ck-led-bulb-dual-function-27-smd-led-tower-wedge-base

The listing for the LEDs needs to say "SRCK compatible," you can't assume they are just by how they look. It's a difference in how the sockets are wired.
What's odd is they don't list that anywhere on the ad. They arent Can Bus compatable but thats all they say. When you seach SRCK compatable 3157 these are like the 3rd listing to pop up.
It works great when the headlight switch is in the off position, and even with it on, the brake light function still works great. Just like the front turn signals, they won't signal which is what makes me think it's an issue with the flasher relay.

In theory, could I swap incandescent bulbs back into the rear and if the issue goes away I'll know the bulbs are the issue?
 
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Burban1998

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You definitely need the led flasher if you do not change the assemblies. Some of the plug and play light assemblies come with the led box which you mount with 2 face tape behind the assemblies.
I've replaced the flasher relay with an LED compatable one. I had the best luck with a Standard Intermotor EFL6, but they will not signal when the headlight switch is in the on position.
 

Burban1998

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Sounds like a plan to me.
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Well there’s One mystery solved. Only issue is the signal light being on with the headlights on. Doesn’t really bug me though.

Now to get these damn switchbacks to function. Can’t figure out why they work with 2 in but don’t with all 4. I have my theories though…
 

someotherguy

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LED's replacing incandescent usually takes a bit of tinkering mostly to solve hyperflash - some fix it with a special flasher, others hack the factory flasher, and some will use resistors.

Switchbacks, however, usually take a lot more tinkering to get them to behave, especially when you have 2 on each side like a GMT400. Most vehicles just have 1 front signal each side (other than the typical small corner bulb.)

What I found many years ago is that even while I had solved hyperflash with a hacked flasher, when I changed from regular LED's to switchbacks, I had to put resistors back into the circuit in order to get the switchbacks to work properly.

Like df2x4 said if you're using the factory style rear socket circuit boards you -must- use SRCK-compatible LED's in the middle (brake/turn/tail) socket. Anything else in there and you're fighting an uphill battle that you can't win until you get the correct part.

The turn signal indicators in your cluster illuminating full-time is an annoyance that comes with most LED swaps and it can vary in degrees. It's coming from voltage feedback on the circuit as the LED's aren't sucking it all down like an incandescent would. I've found on GMT800's it can be really annoying with also unevenly lighting up segments of the side mirror turn indicators. The quality of LED's I used seemed to affect this, too - when I replaced the cheapo no-name LED's in the small corner bulbs with Phillips brand, it improved the situation slightly.

You -can- get switchbacks working on a GMT400, I've done it, but the products you choose and how you install them is still a bit of an art form and luck. Just know that it can be done. This is my '94 back in the day with ALL external LED's and switchbacks. The flash rate is a little off due to running a hacked flasher for the turn signals in combination with resistors to make the switchbacks work, but it was slower than the typical hyperflash so I was OK with it:
xc_hide_links_from_guests_guests_error_hide_media


And my Chrysler 300 SRT8 with switchbacks, too. A little easier in general since there's just the 1 bulb each side, but took using resistors to fix the flash rate because the flasher is incorporated in the BCM.
xc_hide_links_from_guests_guests_error_hide_media


One that was a real PITA was my '97 Suburban where I got the newer "projector style" switchbacks, I think from Autolumination/Superlumination. They worked fine with the truck not running, but once it was running they would begin to flicker/strobe and behave erratically. Never did figure it out but I believe it was an overvoltage situation (the switchbacks are very finicky on the voltage) because the 'Burb was LS-swapped and those PCM-controlled alternators often charge at a higher rate, at least at a casual glance.
xc_hide_links_from_guests_guests_error_hide_media


Richard
 
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Burban1998

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LED's replacing incandescent usually takes a bit of tinkering mostly to solve hyperflash - some fix it with a special flasher, others hack the factory flasher, and some will use resistors.

Switchbacks, however, usually take a lot more tinkering to get them to behave, especially when you have 2 on each side like a GMT400. Most vehicles just have 1 front signal each side (other than the typical small corner bulb.)

What I found many years ago is that even while I had solved hyperflash with a hacked flasher, when I changed from regular LED's to switchbacks, I had to put resistors back into the circuit in order to get the switchbacks to work properly.

Like df2x4 said if you're using the factory style rear socket circuit boards you -must- use SRCK-compatible LED's in the middle (brake/turn/tail) socket. Anything else in there and you're fighting an uphill battle that you can't win until you get the correct part.

The turn signal indicators in your cluster illuminating full-time is an annoyance that comes with most LED swaps and it can vary in degrees. It's coming from voltage feedback on the circuit as the LED's aren't sucking it all down like an incandescent would. I've found on GMT800's it can be really annoying with also unevenly lighting up segments of the side mirror turn indicators. The quality of LED's I used seemed to affect this, too - when I replaced the cheapo no-name LED's in the small corner bulbs with Phillips brand, it improved the situation slightly.

You -can- get switchbacks working on a GMT400, I've done it, but the products you choose and how you install them is still a bit of an art form and luck. Just know that it can be done. This is my '94 back in the day with ALL external LED's and switchbacks. The flash rate is a little off due to running a hacked flasher for the turn signals in combination with resistors to make the switchbacks work, but it was slower than the typical hyperflash so I was OK with it:
xc_hide_links_from_guests_guests_error_hide_media


And my Chrysler 300 SRT8 with switchbacks, too. A little easier in general since there's just the 1 bulb each side, but took using resistors to fix the flash rate because the flasher is incorporated in the BCM.
xc_hide_links_from_guests_guests_error_hide_media


One that was a real PITA was my '97 Suburban where I got the newer "projector style" switchbacks, I think from Autolumination/Superlumination. They worked fine with the truck not running, but once it was running they would begin to flicker/strobe and behave erratically. Never did figure it out but I believe it was an overvoltage situation (the switchbacks are very finicky on the voltage) because the 'Burb was LS-swapped and those PCM-controlled alternators often charge at a higher rate, at least at a casual glance.
xc_hide_links_from_guests_guests_error_hide_media


Richard
Thanks for the detailed response, I'm going to test my battery and see if that isn't causing some issues. When running down the highway for a while, the drivers drl tries to switch over but just flickers.

I noticed that the volt meter in the dash is always around 14-15V which would indicate that it's charging. I'm thinking that the switchbacks may be getting an erratic enough voltage to prevent them from staying white.
 

df2x4

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I bet adding some resistors in line with the switchbacks would fix your issues. I've seen a few other people solve similar problems that way.
 
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