Car Stereos: 04 Chevy Trail Blazer, chevy trail blazer, vehicle data bus

Question
QUESTION: Hey Brian,

I have an  04' Chevy Trail Blazer, with bose and OnStar. In an earlier question that you answered, you mentioned that if the vehicle has a bose system it was necessary to get the more complicated wiring harness to allow the bose amplifier to continue working. If I am planning at a later date to add an amp and sub, or even a bazooka with an amp already integrated, will that become another complication?

Thanks,

Scott

ANSWER: Hi Scott,

In your Trailblazer, the main complications will come when you're replacing the factory radio with an after-market head unit.  It's the connection between the factory radio and the data bus system, and the connection between the factory radio and the Bose amplifier, that cause the problems; these connections need to be replicated when you're installing a new head unit.  It doesn't really make the installation more difficult; just more expensive, because you need the specialized adapter.

Adding an amplifier and subwoofer to the after-market head unit, or even to the factory system, doesn't cause the same sort of problems, because it doesn't affect the head unit's connection to the vehicle data bus. That type of installation would be much the same as in any other vehicle.

Hope this helps!

Brian  

---------- FOLLOW-UP ----------

QUESTION: Hey Brian,

Not sure if you can answer questions about specific wiring harnesses, but it seems this one is a popular one so hopefully you will know!

I just received my GMAH24B harness to connect to the data bus system, and I've labeled and visually matched up all the wires, before going to the trouble of hard mounting them (I'm moving forward with the utmost care as I have no experience in these topics). After matching up all the wires, I am left with a few unmatched options. On the head unit side, an antenna and car phone wire, and on the other side, an antenna and an illumination wire. First I have no idea what the illumination one is for as the instructions included aren't very clear, and second, if my car has no phone or power antenna what do I do with the loose wires?

Sorry for the lengthy description of my issue,

Scott, 04' Chevy Trail Blazer.

ANSWER: Scott,

An illumination wire simply tells your new head unit when your vehicle's lights are switched on.  Some head units have an automatic dimmer that reduces the display brightness at night, when you're using the headlights.  If your new head unit doesn't have such a wire, then you don't need to connect the illumination wire in the harness to anything.  Just make sure it's insulated, because if it gets grounded to chassis metal, it could blow your vehicle's instrument lighting fuse.

A car phone wire is typically used with a separate after-market hands-free phone kit, rather than with any vehicle wiring.  Otherwise it won't be used.  Again, make sure it's taped off, because if it touches chassis metal it will mute your head unit.

I'm pretty sure your Trailblazer has a standard mast antenna on the front fender.  If so, then you shouldn't need to use the power antenna wire.  However, many vehicles are starting to come with imbedded aerials in the rear glass.  In this case, the power antenna wire would need to be used, because there's typically an antenna amplifier in these cars, and it's activated by the power antenna wire.

Hope this helps!

Brian  





---------- FOLLOW-UP ----------

QUESTION: Hey Brian,
we spoke before about the necesary parts for putting a new headunit in my 04 trail blazer. I have got the correct harness from peripheral and wired everything up as it is suposed to be (minus the illumination and antenna), but when I turn the stereo on the sound is very quiet, even when the volume is turned all the way up. To get any sound at all the deck has to be on a volume of 35+ out of 50.

I have done a basic trouble shoot simply by replacing the possible parts that could be causing issues. The deck is fine as it works in other vehicles, and I got a second peripheral harness, both of which lead to the same end result.

Since all the wires are hooked up properly, the deck is fine, and the harness appears to be fine, im not sure what the issue could be.

Thanks,

Scott 04' Chevy Trail Blazer

Answer
Hi Scott,

Unfortunately, I've never used the Peripheral adapter you mentioned, so I don't have any experience with it.  I took a look at the owner's manual, which appears to show a volume adjustment dial built into the adapter.  Have you tried adjusting this?  

Sorry, but I don't have any other suggestions to add.  You might try calling PAC's tech support line at 866-931-8021.  (PAC Audio currently owns the Peripheral brand).

Generally, when I install into these vehicles I use Metra's GMOS-04 adapter.  You might want to give it a try if you aren't able to get the Peripheral piece working properly.

Good luck!

Brian