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2004 gmc envoy_slt
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432 Posts
Discussion Starter #1 (Edited)
Hey guys, I'm new to this site but was a member of an Explorer Forum for about 3 years so I am familiar with how these work. The Explorer was sent to the junker for the cash for clunkers program and I was awarded with my mom's 2004 Envoy.

I have already converted the front low beams and fog lights to HID (6000k lows and 5000k fogs). I have done a full interior LED conversion and changed out the bulbs in the reverse lights and license plate lights to LED. I am looking to take the next step with blinker bulbs and brake bulbs.

I am familiar with doing LED taillight bulbs because I changed them out on my old Explorer and used load resistors to get them to flash normally. I wanted to find an easier fix for this though rather than tapping into a bunch of wires.

I have taken some pics of the blinker relay. It is a GM 12450284 relay that is used on most GM trucks. It operates the blinkers on the truck and for the trailer lights (when using). I've included pics of where the relay is located and how to remove it. Use a flathead screwdriver to push the small tab down and slide the clips to the larger holes. It should slide out the whole thing. Then push back the grey clip to loosen the hold on the relay. You may need to use a flathead to pry out the relay too. Be careful not to damage it. Here are the pics and now for the good news.













I have found a solution to the relay. I have found a product online called named GM LM455. It is the same 10 pin relay except with the right load for LED bulbs or a mixture of LED and incandescent bulbs. I am ordering one and will see what the outcome is. Here is a pic.

New Relay:
 

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2006 chevy trailblazer_ls
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76 Posts
awesome man! hope it works out! definitely keep us posted!!
:thumbsup:
 

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2004 gmc envoy_slt
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432 Posts
Discussion Starter #3
Wow, already a sticky. I guess this has been a question for everyone for a while. I will definitely update once everything is in.
 

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2009 chevy
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25 Posts
I got the LM 487 (Napa) and it works perfectly for all my LEDs EXCEPT the tail running lights (the ones that come on at night). I don't know why, but everything works fine, including cruise control and the brake lights, but the tails just don't come one when the headlights do. Are you having the same problem?
 

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2004 gmc envoy_slt
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432 Posts
Discussion Starter #6
Mine just came in the mail today and I have to say I'm disappointed.

It clearly says "LED" on the front, but I still have a hyperflash issue. I pulled the relay apart and compared it to the OEM relay and they have almost identical inside parts except one piece (which I don't believe makes a difference but I could be wrong).







Clearly says LED but definitely no improvements with the flasher. A little upset.

How much was the LM 487 and where was it purchased? Do you have LEDs at all corners?
 

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2009 chevy
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I got the LM487 from Napa and they charged about $75. They didn't have it in store but they got it there in about 5 hours, good customer service. I have LEDs everywhere except the main front turn signals (lost them somewhere).
 

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2004 gmc envoy_slt
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432 Posts
Discussion Starter #8
I got the LM487 from Napa and they charged about $75. They didn't have it in store but they got it there in about 5 hours, good customer service. I have LEDs everywhere except the main front turn signals (lost them somewhere).
Alright because my new relay says LED on the front and has hyperflash, but I do have LEDs in the front and the back. I just wonder if that's why I'm having the problem.
 

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2004 gmc envoy_slt
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Discussion Starter #10
Here's a link to Napa's online catalog for your '04 Envoy that describes the LM455 as "w/o LEDs" and the LM487 as "w/ LEDs". I think whoever sold you that LM455 got you good.

http://www.napaonline.com/masterpages/NOLMaster.aspx?PageId=430&CatId=11&SubCatId=10
Thanks for the help man. After doing a bit of research I found the LM487, then I came back here and saw you had the same reply. I'll be taking a trip out tomorrow to a NAPA to get the flasher I need. Thanks a bunch :hail:
 

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2009 chevy
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No problem, man. I'm still having the problems with the tail lights. If you have the same problem after you get the 487, let me know.
 

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2004 gmc envoy_slt
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Discussion Starter #12
It is confirmed. The LED flasher relay is the LM487 from either Napa Auto Parts or from LEDlight.com (http://www.ledlight.com/electronic-led-flasher-lm487.aspx).

I just put it in and had a nice drive so I tested out cruise control, which has gotten criticism for not working with this flasher. Functioned fine and the flash is finally normal as well. I believe this flasher is electronic and I was worried about it not clicking with my turn signals but it still clicks a relay, which is good.

If you have LED signals and don't want to get a million load resistors, this is the easiest fix.

Benjamin, I haven't ridden with the relay at night yet but I will let you know if I have any issues.
 

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2009 chevy
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It is confirmed. The LED flasher relay is the LM487 from either Napa Auto Parts or from LEDlight.com (http://www.ledlight.com/electronic-led-flasher-lm487.aspx).

I just put it in and had a nice drive so I tested out cruise control, which has gotten criticism for not working with this flasher. Functioned fine and the flash is finally normal as well. I believe this flasher is electronic and I was worried about it not clicking with my turn signals but it still clicks a relay, which is good.

If you have LED signals and don't want to get a million load resistors, this is the easiest fix.

Benjamin, I haven't ridden with the relay at night yet but I will let you know if I have any issues.
So what's happening is my RR park (#17) and LR park (#14) fuses are blowing when my lights turn on, disabling the parking lights. Tried with and without resistors. Are you having the same prob?

For now I'm just going to put my old filament bulbs back into the park/brake sockets so I don't get pulled over for no parking lights or license lights.
 

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2004 gmc envoy_slt
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Discussion Starter #14
So what's happening is my RR park (#17) and LR park (#14) fuses are blowing when my lights turn on, disabling the parking lights. Tried with and without resistors. Are you having the same prob?

For now I'm just going to put my old filament bulbs back into the park/brake sockets so I don't get pulled over for no parking lights or license lights.
Well I didn't realize the orientation of polarity with the new LED wedge bulbs when I put them in. I managed to blow all 3 fuses, which include BRAKE (#34) RR park and LR park. I didn't realize that in doing this, the fuses that control the license plate lights would also be blown since they are in the same circuit as those park lights. Then after getting the orientation of the bulbs correct, I was able to only get the brake lights to work but I had quad brake lights too and this was ridiculously confusing.

I opened up and realized when the park lights came on I had a ground directly connected to positive, which is the reason fuses are there, to prevent overload of a circuit and a potential fire. I am going to solder up my own connections in the circuit board and post pictures up soon. Maybe it'll shed some light on your problem.
 

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Discussion Starter #15 (Edited)
So what's happening is my RR park (#17) and LR park (#14) fuses are blowing when my lights turn on, disabling the parking lights. Tried with and without resistors. Are you having the same prob?

For now I'm just going to put my old filament bulbs back into the park/brake sockets so I don't get pulled over for no parking lights or license lights.
Well I'm using my original OEM wedge bulbs right now but it's only because I didn't realize the polarity of the LED bulb when I installed it, which is why I managed to blow out every fuse and almost rip my hair out.

I am soon going to show a tutorial thread and show how I'm going to orient the polarity. It should be interesting.
 

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2003 gmc envoy_slt
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Well I'm using my original OEM wedge bulbs right now but it's only because I didn't realize the polarity of the LED bulb when I installed it, which is why I managed to blow out every fuse and almost rip my hair out.

I am soon going to show a tutorial thread and show how I'm going to orient the polarity. It should be interesting.
I have a SLT also. I have 4 RED, 4 AMBER 27 SMD #3157 bulbs and 2 AMBER #194 bulbs on the way to replace all of my running, brake, and turn/flasher bulbs.
Polarity issues aside does the LM487 work as advertised in all modes without modifications?:thx
 

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2004 gmc envoy_slt
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Discussion Starter #17 (Edited)
I have a SLT also. I have 4 RED, 4 AMBER 27 SMD #3157 bulbs and 2 AMBER #194 bulbs on the way to replace all of my running, brake, and turn/flasher bulbs.
Polarity issues aside does the LM487 work as advertised in all modes without modifications?:thx
Surely works for me. I read about it in a Trailblazer SS forum and some were having issues with cruise control not working since the relay runs on lower current.

I haven't had any issues at all with it though. All of the polarity issues I had were from the type of LED bulb I bought, not the relay itself. Everything still works great and its got a normal flash. It's a direct plug-in. Just read the beginning of this thread to see how to remove the relay, then get the new LM487 and pop that baby in.
 

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2004 gmc envoy_slt
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Discussion Starter #19
Would you have to convert every turn bulb to LED?
No not every bulb. It might even work with incandescent bulbs. I know a mixture is fine because I'm pretty sure it's electronic, so it doesn't rely on the load of the bulbs.
 
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