LED turn signals = a few issues (not hyperflash)
 

ok before the comments all start on legal, "why", etc. understand this is not the first time i have done LED conversions I like them that's why I choose to do them and figure out these issues. I changed all the interior courtesy lighting over to soft white LED's as opposed to the normal cool blue LED's that most people use. Then i moved on to exterior lighting here is what is going on:

for Christmas i got clear parking lamp housings
LED flasher relay
2x 3157 LED switchback bulbs, these exact ones - 2X 3157 60SMD DUAL COLOR SWITCHBACK WHITE AMBER TURN SIGNAL LED LIGHT BULBS 3057

for clarity
parking lamp = housing under the headlight, no fogs in my case
corner marker = amber bulb in headlight fixture.

I installed them this afternoon and everything seemed fine until I turned the headlights on
once I turn the parking lamps or headlights on both of the turn indicators in the cluster turn on just slightly dimmer than when the blinker is on. when you turn the blinker on you can see it get noticeably brighter then operate normally until the blinker shuts off then they go back to dim. I figured this had to have something to do with the relay so i went back to oem with no change. On a guess i figured there was a shared ground between the parking lamps and the corner markers. I pulled the corner marker bulbs and that fixed the cluster lights. since i am guessing somewhere on "the road home" the wiring for both of those lights on each side intersect i figured it was most likely a difference in load causing this issue so i replaced the corner markers with LED's (194 amber) and that fixed the cluster issue.


Issue #2 this is unresolved

during the day if you turn the blinker on the parking lamp flashes amber then shuts off - this is normal and correct
during the night with parking/headlights on the parking lamp is illuminated white. Per the description from the seller on these specific lamps when you turn the blinker on the white is supposed to turn off and the amber should flash then when you turn off the blinker after 1-2 seconds the white should turn back on. I believe this makes them type 2 but in this situation it doesn't really matter.

what is actually happening is headlights on = white parking lights on, blinker on = white parking lights stay on the entire time and the amber dimmly flashes as well. It's so dim that you cannot see it unless you are right up on it. The corner marker LED's operate fine and alternate with the parking lamp blinker.


The switchback white is the traditional blueish white LED color IMO it clashes with the natural white 4300k HID headlights i have already since they almost look purple so i'm not a fan of these so far. i'm looking for ideas as to what may be causing this situation or if anyone has had this problem before either way. My mind is kind of leaning towards needing to change the taillights to LED as well. I have never had to do an all or nothing LED install before but this is the first time i have had a vehicle that had a mechanical relay vs being controlled by the BCM or similar hardware. In the mean time I ordered and all amber set of 3157 LED bulbs just to be safe also so i can decide which way i like better. It's not my daily i'm just messing around with all of it so i have a good understanding. I ran out of time tonight to troubleshoot much more in depth. I'm sure if i put the incandescent bulbs back in it will be fine but that's besides the point in my mind.

so my idea as of now is install LED taillights and see if that fixes it. If this is the case this brings up another issue in my mind and that's towing. If this fixes it does that mean the second I hook up a trailer with traditional bulbs i'll be right back in the same spot? if that's not the solution then i will just assume LED's i bought off ebay are probably just junk. that's where i'm at as of right now and i'm looking for some opinions.

Thank you

What year is the vehicle?

The wiring of these can be pretty strange in that the stock bulbs have to flow current in both directions to get the corner marker to blink off when the turn signal in the parking light blinks on. This causes issues when switching to leds in the parking lights and turns as the leds do not allow current to reverse direction like a filament does. When I did something like this years ago now and I had similar issues, but I don't recall what I did to fix the issues I had. You have another layer of problems added by going with switchbacks, which have an entirely higher level of electronics that these older blazers were never meant to deal with. Trying to run current the wrong way through something like your parking lamps can cause all kinds of weirdness.

Rear lights being led or incandescent shouldn't matter. You may be able to disconnect the corner markers from the parking lights. If you run it this way, you might be able to get a 'normal' current flow through the parking lamps. Then you could tie the corners into the turns only or into the parking circuit only. Or you can try to figure out how to use a 5 pin relay to flash off with the turn signal.

I had to use load resistors up front in my 04 when I converter to all LED's, despite using a different flasher relay. It's because of the way the current goes through the bulbs in both directions as Thogert mentioned. Odd wiring if you ask me... but after putting load resistors on the turn signal wires at the park light bulb under the headlights, all was well in my case, even after converting the tail lights fully to LED as well.

2002 4dr 4wd

When I switched the corners to led everything worked right as far as blinker operation. No hyperflash, no cluster lights, but the switchbacks didn't work properly still. The white light stays on 100% of the time and the amber flashes but can't be seen. Picture is of the front end during the day with no lights on.

What were your symptoms that made you decide to add the load resistors? My understanding is 3157 has 12v+ for parking light, 12v+ for turn signal and 2 grounds on the other side. If it was a bulb there is the same thing across two filiments. A switchback should see the constant 12vdc of the parking and when it see's 12vdc for turn it's supposed to cut the 12vdc to the parking white light and only power the amber. That's what has me thinking the problem is the actual switchback. Plus the "white" light on these is somewhere in the 8-10k temp range has me pretty certain they are just crap quality. Just wondering if anyone has working switchbacks and what brand they are.

I'm pretty sure I tried it with the corner markers disconnected and the switchback operation was unchanged. I will verify again. Still waiting on another round of LED's to get here. Supposed to arrive tuesday due to the holiday

You could try running the switchbacks off the battery to confirm correct operation. That is what I'd do, but then again I went to school for electrical systems and have fun doing things like that. :icon_shrug:

I did low voltage work for 9 years. I'm not scared to do it, I just never thought about going direct to the battery.... duh. Before I do that my question is what is normal operation for a switchback? Is it when both 12v sources are active the white is supposed to cut off and amber should just blink? Or is the truck relay supposed to be cutting the power to the white light side? I can't imagine the truck should be doing that just based on a normal bulb being dual filament and having low response times on an incandescent bulb.

I'd imagine the switchback should be able to handle either +12V on both the inputs at the same time as well as just the turn signal being at +12V. Seeing as some vehicles do not have DRLs.

The dimly lit turn signal indicators, just like yourself.


These switchbacks are what I ended up with after my first set were crap... The first different set would keep flickering off when the running lights were on... These ones worked great though, and are BRIGHT. Looked great through clear lenses.

http://i.ebayimg.com/images/g/Bf4AAO...D2m/s-l500.jpg


Of course my cheap clean lens lights didn't last long before the lens separated, so stockers went back on for now with regular bulbs :P but that'll be changed back soon.

Ahh yeah lol, I was just looking at those too. I have bought something similar before for my GTO and I had the same issue it fell apart. That's why I ordered the smd only one this time around. That hasn't worked out all that well either. I normally have pretty good luck with eBay LEDS but when it goes wrong it goes really wrong.

oh the LED's didn't fall apart, the light housings themselves did lol the clear lens just started separating from the back of the housing

I actually carried the switchback LED's over to my Corolla from the Blazer when I put the stock lights back on the Blazer. They still work great to this day, almost 3 years later

Attachment 30730

Well the seller replied. They are saying they may have had a production issue and are checking with the manufacturer, refund/replacement pending.

The pure SMD type LED replacement bulbs are all I use to get as well, but it's also worth considering there are different types of SMD LED's, and that's what lead me to try out the ones I posted above.

For tail lights, I searched for years for a direct drop in LED replacement that had good light output, and kept running into the same problem, that is that the brightness was hardly different from running lights to brake lights, making it not very safe...

My solution for those came in the shape of Osram Joule LED modules from newer Ford Mustangs, Chevy Impala LTZ's, and Mercury Mariners. I have a thread here on how I did the conversion if you're interested

https://blazerforum.com/forum/lighti...etrofit-90983/

Led tech improves almost daily. Now with the 5050 smd as far as 3157 bulbs you need about 5-8 5050 smd to equal the same lumen output as its incandescent counterpart. Only a few people are making 3157 with 5050 smd all in China of course. The ones i got arr 5730 smd which is even brighter than thr 5050. Basically its a huge research project (as you know) each time find an led replacement priced where you want figure out what type of LED they are made of find the light output in lumen per smd find incandescent lumen rating compare. I ordered another set of switchbacks this a.m.
2 X Dual Color 3157 High Power Yellow White 5730 20 LED Switchback Light Bulbs | eBay
They are basically the same as the ones with projectors but I only like to use projector style LED'S in fog light or reverse light applications. worst case I will use them if there is a reflector to break up the foward facing light angle which there isnt in these blazer housing. So I will give these ones a try since I forsee a refund in the near future on the original bulbs I got.

Also I found a wiring diagram for the lights I might as well leave it here. It was very helpful in determining the lights as being the issue

And the results are in, the switchback was the issue. New one works fine and looks great. Thanks everyone!