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2003 chevy trailblazer_ls
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Discussion Starter #1 (Edited)
If you're anything like me you like doing things yourself; cheaply, and efficiently.
Doing vehicle mods cheaply requires knowing EXACTLY what you need and how to install it.

When it comes to replacing stock Trailvoy bulbs with LED, there is a TON of disinformation floating around the internet in addition to information being scattered among random GMT and Trailvoy threads.
For someone who isn't familiar with LEDs, it may seem very overwhelming.
Alas, LED replacement is not hard at all. You just need the RIGHT information.
This guide is here to help you get things done RIGHT. That means CHEAPLY and EFFICIENTLY.
*I did this mod on a 2003 Trailblazer, the Envoy might be slightly different*

First, I will cover the interior roof lights.
THE BASICS: Interior
To begin, the Trailvoy roof lights are essentially plug n' play. However, there are two different bulbs used in the 2003 model for some unknown reason.
In my vehicle, I have one "dome" light and 4 "dome/map" lights.
The "dome/map" lights are above the seats in the vehicle (you can push them to turn the front cell on), the one "dome" light is all alone in the trunk area and cannot be pressed.
These lights absolutely suck, I'm glad the '05 and up Trailblazer got some real map lights (meaning the bulbs may be different than mine).

The DOME light takes ONE 212-2 bulb, no modification is needed to install it.

The DOME/MAP lights take 2 T10/194 bulbs EACH. In each light, the rear bulb fits fine. In the "pressable" one, the plastic reflector will need to be modified to accommodate the height of the LED bulb. I simply used pliers to break the little "cup with a hole in the bottom" off so the bulb would fit.


THE BASICS: Exterior
The exterior lights are where things get tricky. The wrong bulb in the wrong socket WILL blow fuses and cause unsafe or undesirable operation.
There are two types of sockets to my knowledge, standard/normal and "CK".
"CK" sockets are identifiable by having the GROUND on the SAME side of the socket. How to identify: http://www.youtube.com/watch?v=V8ONj-NJdjA

Reverse Lights:
The reverse lights take a standard white (or whatever color you'd like) 3157 LED bulb.
They are plug n' play.

Rear Turn Signal Lights:
These take a RED 3157 LED bulb and require a 6ohm 50W resistor to prevent hyperflash.
On the plug into the taillight assembly, the leftmost wire is negative and the second wire from the right is the positive for the signal. The resistor should be installed between these two wires, essentially creating a short.

Brake Lights:
The brake lights require a RED 3157 LED for a CK socket.
Failure to use a CK bulb WILL blow your rear parking light fuses or your brake light fuse located under the rear seat.
As long as you have a CK bulb, they are plug n' play.

Front Turn Signals (under the headlight):
These require an AMBER 3757A LED for a CK socket.
Failure to use a CK bulb WILL blow the front parking light fuse located under the rear seat.
Just like the rear, these bulbs require a 6ohm 50W resistor between the negative and turn signal positive to prevent hyperflash.
Optionally, you can get AMBER/WHITE 3757A SWITCHBACK LEDs for a CK socket.
These bulbs are white for the parking lights and amber for the turn signals. Here are some on a Traverse: http://www.youtube.com/watch?v=I5NOi_-dNmI

Front Side Turn Signals (beside the headlight):
*I haven't modded these yet, some info is unknown*
I do not know what type of socket these bulbs are (I assume CK, but check them yourself to be sure).
They take an AMBER T10/194 LED (you can also get a tiny "switchback" for this socket too: http://www.youtube.com/watch?v=OpDMdxJBRHA )
You do not need a resistor for this bulb (mine has blown before and I didn't get hyperflash).

*Be sure to mount the resistors to metal, they will get HOT!


That's it. :D
Every bulb you can want to replace with LED (except the dash cluster which there's already a thread for).
Hopefully this will help those of you who are lost and will prevent people from wasting money on wrong bulbs and blown fuses like I did!

FAQ:
Q: My LED bulb won't light up?!
A: Flip the bulb 180° and it should work.

Q: My parking lights aren't working in the front/rear?!
A: You have installed a standard LED bulb in a CK socket and blew a fuse. Make sure you are using CK bulbs in the CK sockets and replace the fuses (located under the rear seat).

Q: Only my 3rd brake light is working?!
A: Similar to above, you blew the stop light fuse by using a normal LED bulb in a CK socket.

Q: My turn signals don't hyperflash with the 4-ways but do hyperflash with just the left/right?
A: You forgot a resistor somewhere. You need 4x 6ohm resistors to get the required resistance.

Q: How do I get the dome/map light lens off? It feels like I will break it.
A: The rear of the lens snaps down, there is a tab in the front anchoring the lens to the ceiling. Pull on the lens from the back.
 

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2003 chevy trailblazer_ls
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Discussion Starter #2 (Edited)
UPDATE:
There is no LED replacement for the front turn signals (3757).
However LED CK 3157's are readily available and do fit snug in the 3757 CK socket once you file down the plastic tabs on the side of the bulb.

Here's more information on how to put a switchback in the side marker light.
GMT hyperlinks don't work here...
/f33/led-mod-thread-944/index7.html#post44894
 

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2005 chevy trailblazer_lt_ext
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Hey all, I've replaced all the bulbs inside with led, except the small bulbs on the visors. Has anyone converted these to led? Is it possible? They look more like fuses than actual bulbs. Haven't been able to match them up with what I can find locally. Thanks.

Sent from AutoGuide.com Free App
 

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Discussion Starter #4

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Discussion Starter #6
No luck there. Anyone else have suggestions? My visors have a single bulb.
Like MAY03LT said, not every Trailblazer has the same visor and he doesn't think the bulbs were even meant to be replaced.
My visors don't even have lights, just a mirror.
Your best bet is to take some time and figure out how yours comes apart.
 

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Rear Turn Signal Lights:
These take a RED 3157 LED bulb and require a 6ohm 50W resistor to prevent hyperflash.
On the plug into the taillight assembly, the leftmost wire is negative and the second wire from the right is the positive for the signal. The resistor should be installed between these two wires, essentially creating a short.

Brake Lights:
The brake lights require a RED 3157 LED for a CK socket.
Failure to use a CK bulb WILL blow your rear parking light fuses or your brake light fuse located under the rear seat.
As long as you have a CK bulb, they are plug n' play.

Do these need to be RED in color, or can you use white, because the factory bulbs are not colored.

Just not sure if the intensity of the white LEDs will make the light almost look pink and that is why you are saying to get the red instead of white.

Thanks!
 

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2005 chevy trailblazer_ls
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where is the thread on replacing the lights in the dashboard cluster ?.
 

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2003 chevy trailblazer_lt_ext
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I got tired of my stock bulbs and just swapped the WHOLE bulb and socket, to 3157 to make it cheaper and easier to find switchbacks


Led Turnsignal Bulbs-Make Sure bulb is 3157: http://amzn.to/2r5NGDh
3157 LED Socket Base: http://amzn.to/2rPRMQW
Load Resistors: http://amzn.to/2rhtZsF

I wanted led, and I wanted switchback bulbs so I swapped the 3757ck socket for a 3157, and then picked up the 3157 LED bulbs+load resistors. For me, this was much easier than finding a 3757ck LED bulb (which doesn't seem to exist, as noted earlier in thread) and after some simple cutting/splicing wires I was all done.

Easy to do, look great, works.
 

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If you're anything like me you like doing things yourself; cheaply, and efficiently.
Doing vehicle mods cheaply requires knowing EXACTLY what you need and how to install it.

When it comes to replacing stock Trailvoy bulbs with LED, there is a TON of disinformation floating around the internet in addition to information being scattered among random GMT and Trailvoy threads.
For someone who isn't familiar with LEDs, it may seem very overwhelming.
Alas, LED replacement is not hard at all. You just need the RIGHT information.
This guide is here to help you get things done RIGHT. That means CHEAPLY and EFFICIENTLY.
I did this mod on a 2003 Trailblazer, the Envoy might be slightly different

First, I will cover the interior roof lights.
THE BASICS: Interior
To begin, the Trailvoy roof lights are essentially plug n' play. However, there are two different bulbs used in the 2003 model for some unknown reason.
In my vehicle, I have one "dome" light and 4 "dome/map" lights.
The "dome/map" lights are above the seats in the vehicle (you can push them to turn the front cell on), the one "dome" light is all alone in the trunk area and cannot be pressed.
These lights absolutely suck, I'm glad the '05 and up Trailblazer got some real map lights (meaning the bulbs may be different than mine).

The DOME light takes ONE 212-2 bulb, no modification is needed to install it.

The DOME/MAP lights take 2 T10/194 bulbs EACH. In each light, the rear bulb fits fine. In the "pressable" one, the plastic reflector will need to be modified to accommodate the height of the LED bulb. I simply used pliers to break the little "cup with a hole in the bottom" off so the bulb would fit.


THE BASICS: Exterior
The exterior lights are where things get tricky. The wrong bulb in the wrong socket WILL blow fuses and cause unsafe or undesirable operation.
There are two types of sockets to my knowledge, standard/normal and "CK".
"CK" sockets are identifiable by having the GROUND on the SAME side of the socket. How to identify:

Reverse Lights:
The reverse lights take a standard white (or whatever color you'd like) 3157 LED bulb.
They are plug n' play.

Rear Turn Signal Lights:
These take a RED 3157 LED bulb and require a 6ohm 50W resistor to prevent hyperflash.
On the plug into the taillight assembly, the leftmost wire is negative and the second wire from the right is the positive for the signal. The resistor should be installed between these two wires, essentially creating a short.

Brake Lights:
The brake lights require a RED 3157 LED for a CK socket.
Failure to use a CK bulb WILL blow your rear parking light fuses or your brake light fuse located under the rear seat.
As long as you have a CK bulb, they are plug n' play.

Front Turn Signals (under the headlight):
These require an AMBER 3757A LED for a CK socket.
Failure to use a CK bulb WILL blow the front parking light fuse located under the rear seat.
Just like the rear, these bulbs require a 6ohm 50W resistor between the negative and turn signal positive to prevent hyperflash.
Optionally, you can get AMBER/WHITE 3757A SWITCHBACK LEDs for a CK socket.
These bulbs are white for the parking lights and amber for the turn signals. Here are some on a Traverse:

Front Side Turn Signals (beside the headlight):
I haven't modded these yet, some info is unknown
I do not know what type of socket these bulbs are (I assume CK, but check them yourself to be sure).
They take an AMBER T10/194 LED (you can also get a tiny "switchback" for this socket too:
)
You do not need a resistor for this bulb (mine has blown before and I didn't get hyperflash).

*Be sure to mount the resistors to metal, they will get HOT!


That's it. :D
Every bulb you can want to replace with LED (except the dash cluster which there's already a thread for).
Hopefully this will help those of you who are lost and will prevent people from wasting money on wrong bulbs and blown fuses like I did!

FAQ:
Q: My LED bulb won't light up?!
A: Flip the bulb 180° and it should work.

Q: My parking lights aren't working in the front/rear?!
A: You have installed a standard LED bulb in a CK socket and blew a fuse. Make sure you are using CK bulbs in the CK sockets and replace the fuses (located under the rear seat).

Q: Only my 3rd brake light is working?!
A: Similar to above, you blew the stop light fuse by using a normal LED bulb in a CK socket.

Q: My turn signals don't hyperflash with the 4-ways but do hyperflash with just the left/right?
A: You forgot a resistor somewhere. You need 4x 6ohm resistors to get the required resistance.

Q: How do I get the dome/map light lens off? It feels like I will break it.
A: The rear of the lens snaps down, there is a tab in the front anchoring the lens to the ceiling. Pull on the lens from the back.
This thread is gift that keeps on giving. Just used for reference for 2003 Trailblazer and rear tail/signal/reverse without a hitch. don't know if they were available before but i bought red leds on amazon that were compatible with standard and CK and they worked in both tail and turn. Tomorrow the fronts and fogs. woohoo. Thanks for taking the time to break it down.
 

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Do these need to be RED in color, or can you use white, because the factory bulbs are not colored.

Just not sure if the intensity of the white LEDs will make the light almost look pink and that is why you are saying to get the red instead of white.

Thanks!
Zombied thread --- good info....

About RED LEDs in red lenses.......... a WHITE LED is broad spectrum in that it produces from near infrared ... to near ultraviolet, and the red lens will just block all but the red color from the LED and only allow red to show through it.

This would be seriously wasting the energy of the other wavelengths.

Using a RED LED that only produces red light, will allow more emission of visable light that won't be blocked by the red lens

IOW ... RED LED through RED LENS equals greater brightness ... which is what we're after... right?
 
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