I recently completed a full exterior LED upgrade on my 2002 Blazer, but I'm not satisfied with the headlights.
I have several questions I need to ask, because I've been banging my head against how to do a full and complete LED upgrade for months now without hiring or consulting a professional.

I bought a set of Sealight HB3 and Hb4 LED lights from Amazon and aftermarket light assemblies because my OEM ones were cracked and faded.

Sealight LED lights

Aftermarket housing

1: The HB4 doesn't fit.
When installing the LEDs into these aftermarket assemblies, I noticed that the HB4 lights don't fit in the inside socket. The HB3s fir in both sockets, but the HB4s only fit in the outside socket. I thought this strange and tried installing my old halogens in the new assemblies and I encountered the same problem. The HB4 halogens don't fit in the inside socket. I began doubting myself from the very beginning and though maybe I had the HB3 and HB4 swapped this whole time before doing the upgrade. So I installed them how the naturally fit. HB4 on the outside (low beam I believe) and HB3 on the inside. I consulted my owner's manual and this seems correct. I just need to double check.

2. Weird beam patterned and not bright enough.
I haven't tested the LEDs in the OEM assemblies yet, but these aftermarket ones seem to not shine light correctly. Its bright, but its not bright enough, and I see light splashing where I don't think it should. Are these light assemblies I bought good for LEDs? I don't know if there something LED specific I should buy.

3. Daytime running lights always at 100% brightness.
With the halogens I noticed that my DRLs are usual at a fraction if their maximum brightness, but the LEDs are always at full brightness. I'm starting to doubt myself but the variable brightness thing and that the halogen DRLs were always at 100% and this is just my imagination. But, I also want to make sure these LEDs I have work with DRL properly if anyone has seen them before. I suppose they seem fine, but just wanted to be sure.

EDIT: 2019-11-18-1518

Ok, so my DRLs actually don't work at all. Is something like that specific to the light itself? Maybe incompatible LED lights, or is there some rewiring involved?

After driving for a bit, I also noticed my turn signals are flashing at hyper speed. They were not doing that before when I put the LEDs in, so I don't know what happened.

 

Bump.

 

I had actually spoken to an engineer who specializes in automotive lighting and he told me that the housings for these vehicles are absolutely not designed for LEDs or HIDs. You would have to have a custom housing that was fabricated for the sole purpose of them to actually be somewhat functional and road legal / not blind other drivers.

That being said, the Amazon housing you linked has absolutely terrible reviews so I don't get why you went with that. CarID has a few aftermarket LED housings but I'd honestly just buy another OEM set.

 

I bought those from Amazon because I wanted to go for a colorless set of turn signals lenses that match the headlights. I will be returning them for another OEM set.

 

EDIT: 2019-11-18-1930



I'm now experiencing a weird my Blazer is having a difficult time starting as if the battery were dead. Its done this every time starting it after it had been driven for a good amount of time to charge the battery. After starting I see the volt meter at 15V, so it is charging then drops to 14V while running which is normal.



Could the LED lights be leeching power while off? I still need to troubleshoot which ones, of not all.

 

Near weekend update on this.

So two observations I noticed on the hyper-flashing. My turn signal only hyper-flashes when the parking lights are off. While on, everything flashes are a normal rate.
That being said, when the parking lights are on (I mean the amber colored side bulbs on the headlight assembly -- those are LED too), I noticed that the turn single like to alternate between the parking light and the bumper light while flashing. Not sure what is causing that. Just wondering if anyone has seen or heard of this before. I have digital turn signal relay coming in soon.

As for the headlights. I put the stock halogens back on until I figure out a more proper LED compatible housing and something that also properly functions as a DRL.

 

Maybe you covered this and I missed but when you put in LED for the turn signals they will flash faster without a resistor in line, Most people add a resistor or use a special flasher for LEDs,

Full disclosure I have never done this successfully just laughed at the troubles my son has created on his truck.