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2003 chevy trailblazer_lt_ext
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interface kit

What is the purpose of the interface kit?

I have an '03 with onstar and I just want to install a cd player that has an mp3 jack. I saw a video on youtube with some weirdo running a bypass wire to the fuse box but I was hoping it is not that complicated to install a cd player.:D:D:D:D
 

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non_gmt360 trailblazer_lt_ext
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What is the purpose of the interface kit?

I have an '03 with onstar and I just want to install a cd player that has an mp3 jack. I saw a video on youtube with some weirdo running a bypass wire to the fuse box but I was hoping it is not that complicated to install a cd player.:D:D:D:D
you will need an adapter harness like the gmos-01 if you want everything to function like factory, such as having chimes, and the radio staying on after turning igniton off until you open a door. If you dont care about chimes or the retained accessory power, you can just get a regular wire harness, and then run a switched 12v power from the harness under the steering wheel to the radio for your acc. power.
 

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2003 chevy trailblazer_ls
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Since you have OnStar on ur truck you will need the proper interface to keep OnStar working, installing a cd player is pretty much straight forward because all you do is attach the same color wires. The interface keeps the chimes like door open, handbrake, low fuel, and any other chimes, and it allows OnStar to function as well.
 

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Stay away from scosche products, if you want to figure out wat you need to do the install then head over to Metra's website and look up ur truck, then buy the part from Ebay or amazon
 

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non_gmt360 trailblazer_lt_ext
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onstar is a non option now in an 03.. those are analog systems up until 05 or 06 when they switched to digital.. so unless previous owner spent the money to do the analog to digital conversion the onstar is useless, so I wouldnt worry about the onstar features.. Mainly the adapter will allow you to keep chimes, and retained accessory power.. thats it..
 

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So if I do not care about the chimes/accessory power (which I do not).

basically:
take old cd player out
set up mounting kit
install cdplayer into mounting kit
connect the adaptor to the aftermarket cd player
connect the cdplayer to the mount
button everything up?
 

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non_gmt360 trailblazer_lt_ext
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yes except you will need to run a switched 12v power from somewhere. the factory radio gets a turn on signal through the data bus - hence the need for the adapter and thats how chimes, and the retained accessory power works also.. so if you dont use an adapter like the gmos-01, you will need to run a 12v switched power from somewhere to the radio along with connecting the radio to the factory harness.
 

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Hi there,
I know I'm fairly new here as I just got my Trailblazer only a couple of months ago, but I just replaced the stock deck and speakers on the Trailblazer as they were pretty crappy. I searched hi and low for a write up on how to remove all the dash parts without breaking them and couldn't find anything that really described a step by step process, and parts you need to do this. So I figured I would do a write up on a step by step, photo included instructions on how to replace a stock stereo. So here goes!

My vehicle: 2004 Trailblazer LS 4.2L, NO Onstar

First things first, as you're dealing with electrical components disconnect the battery. I know that in some of these pictures the stereo and lights are on, and thats because it was -16c and I had the engine running.... up until I brought out the space heater then disconnected the battery.

1) Once you've disconnected the battery, start by removing the two lower 9/32 bolts at the bottom of your kick plate (circled here in red)



2) Then remove the upper two 9/32 bolts holding the kickplate. The kickplate my fall on you, so just watch your head.


3)Then remove the two bolts holding the gauge surround on the outboard side of steering wheel.


4)Then remove the one bolt on the inboard side of the steering wheel.


5) Remove the two phillips head screws just above the gauges.


6) Remove the phillips head screw in the pocket right next to the two 12V connectors.


7) Pop out the dash and disconnect the headlight and fog light connectors


8) Removing the dash surround is a bit of a pain in the ass. It will take some convincing. Make sure the column is fully down, and the shifter is all the way back in 1st gear. Once you've got it popped off remove the rear wiper connector, the 4x4 selector connector, and the two 12V connectors.


9)Once you've got the dash out, you can remove the stock stereo unit by removing the 3 bolts that hold it in and disconnect the connectors on the backside of the stereo.


10) Here are the additional items you need to install with your new deck. From left to right:

a) Radio Shack GM antenna adapter - P/N 12-1336 - Cost $5.00
b) Scosche '92-UP Dash install kit - P/N GMT2049F - Cost $16.00
c) Axxess GMOS interface kit - P/N GMOS-01 - Cost $125.00

I'm pretty sure you can find these same parts online for a lot cheaper, but as I was impatient and wanted to install this deck over the Christmas holidays, I decided to bight the bullet and get them from some local shops. I made the mistake of getting the 2004-UP GM dash kit install kit which didn't work, so don't get confused as I did. I've been told that you don't really need the interface kit, that you can tie into your ignition switch, but I figured the Trailblazer has a lot of electronics and not to mention immobilizers, passlock....etc so I didn't want to risk tapping into something I shouldn't have.


11) This is what you get in the Axxess interface kit. It took some reading and a trip to the local car audio shop to make heads or tails out of this, but its actually fairly basic. The instructions are pretty vague as well, so I'll try my best to describe how this goes together.



12) There are two plugs that have wires that get connected to the aftermarket deck. The strange thing is, they come off of two different connectors. The orange wires you see taped up together in the first picture is the dimmer light and mute wire which my deck doesn't have.

First picture:

Black is Ground
Yellow is 12V
Blue Remote wire for aftermarket/factory amps
Two Greens Rear speakers
Two Purple Rear speakers



Second picture:
White Wires Front speakers
Grey Wires Front speakers
Red is ignition wire
Blue another blue remote wire
*The taped bundle is for systems that have Onstar and Navunits, mine does not so I taped them off.

All depending on your stereo, the colours of the wires that coming off your deck harness could be different from what the interface has. Fortunately my JVC deck had identical colours as the interface.



13) This is the stereo harness and interface completed. I thought I had a picture before I taped it all together... guess I got a little ahead of myself there! The guy at the local stereo shop said to tie both remote wires together from the deck harness, and both blue wires from both connectors of the interface. I also tied in my own remote wire as I plan on installing an amp and sub later on. The black wires and connectors you see are to extend the wires from the one connector to reach the JVC harness.


14)This is what you get in the Dash install kit. There are two spacers that are attached on the main dash face you will need to use, so don't loose them. The other clips that are semi-attached to the unit that have slashes through them in my picture need to be removed as they interfere with the install. You'll see when you try and put the unit in.


15)This is the kit put together and test fit in the vehicle. I wasn't too impressed with the fit as it seemed a little narrow for the bolt locations, however it did work. The area I circled in the picture is a nice place to fit the bulky interface brain. You can also see I strung in some RCAs for future sub install. Be careful if you're poking your hand around the backside if youre stringing any RCAs or Remote wires as the metal back there is unbelievably sharp! Don't forget the two spacers that come with the dash kit!


16) Once you've got your dash kit figured out, you can go ahead and plug the interface kit connectors to the factory connectors. Its a lot easier to install the deck to the dash kit before installing the dash kit. Here is my new JVC deck installed on the dash kit. It fit great inside the dash kit.



17) At this point the installation is reverse order in which you took it all apart.

18) Here it is! All installed! Looks and works Great!



Make sure your 4x4 switch is back in 2WD... I bumped it while taking everything apart and drove around in A4WD for a few km before realising. The stereo stays on after the engine is turned off and key is removed, until the doors open just like factory. Only difference I've noticed is that the door or key chime is slightly different and only comes out of the driver side door speaker.
I hope I didn't forget anything, but if you've got any questions I'll try my best to answer them!


I connected everything correctly, I think and hope lol, when I turn on the radio I have sound but when I turn it up the volume it doesn't change and the volumes stays very low. Any ideas what I did wrong ?
 
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