Hi guys, been away from car audio for many years but I used to be WAY into it with custom installs etc back in the day.

I recently decided to add an Alpine CDE-123 to my 2007 Trailblazer so I could use my iphone hands free and as an audio source.

Install went fine with a headunit install kit from Candian Tire and a wiring harness from my local car audio shop. I skipped out on the "retain your chimes" adapter for now.

After installing, everything seemed fine until I went to fade the speakers. I found out I wasn't getting any audio out of the back speakers. I was just about to leave for vacation so I left it.

I had just had a new heater core installed in the truck so I assumed the mechanic just didn't snap the rear speaker harness back together properly.

I took it back to his shop and he checked all connections and said everything was fine. When I got the truck back, he told me the front speakers had stopped working so now I suspect the head unit was screwed from the start.

I'll be taking it out tonight and putting the stick unit back in and double checking all connections myself at the same time.

One thing concerns me and that's the fact that the head unit required a switched power source. I used my multimeter and located a brown wire under the dash that had 12volts only when teh keys is on so that's what I tapped into.

Long story short, I want to get this thing working and when I do, I'm going to want the steering wheel controls to work.

Have I buggered things with this brown wire tap? Does anyone here have experience with the Trailblazer with no OnStar and with rear radio controls (I assume those won't work after I install the Alpine).

Thanks
Mike

 

Firstly, I'd be surprised if you've retained your steering wheel controls after the new deck install. As far as I know, you'd have to install a Steering Wheel Control Adapter that will give you those controls back, as the new deck isn't set up to receive signals from the steering wheel... (someone correct me if I'm wrong)
>>>Link to Steering Wheel Control Adapter<<<
Hope that helps with that portion of your problem.

As for the loss of rears, and then all speaker functionality - I don't see it having anything to do with that brown wire.
Does the unit still power up as usual? If so, then my guess is that the connection that were made with the wiring harness have come apart...

 

I found out about the steering wheel module. I'm going to remove the head unit as I think it's really mesed up. The rear speakers weren't working, I had the mechanic check all the wiring that he had touched and it's all fine but now the front speakers dont work

If I power off the head unit, turn off the truck and then start it again, the head unit just powers itself on again

I'll post what I find out with this ad the whole switched 12volt in a trailblazer thing seems to be a mystery to many

Thanks
Mike

 

Just a suggestion,you should have considered using a pac module or access module, which would have saved some time

 

So it turns out that both rear speakers were blown. I took the Alpine head unit into my local Alpine dealer and they bench tested it. The amp section was blown.

Here's where it gets messy. I live in Ontario Canada on the border with Michigan. I bought the head unit off Ebay so the seller went AWOL when problems arose. He actually wanted to charge me $45 to send the radio for repair.

I wound up sending it to United Radio Service myself. They kick ***! Talk about a company with great service and a very systemized and organized approach.

NOW...rear speakers have been replaced, head unit is back. While this was all going on I installed a new battery and an alternator only to find out the trouble was due to corroded wires under the rear passenger seat.

Now I'm cautious....was the radio fried because of the wiring under the seat? Did I fry it by tapping into the brown 12 volt wire under the dash? Did the rear speakers blowing up cause the head unit to fry?

Questions:
Is there a better switched 12 volt wire to tap into in a trailblazer?
Can I install an inline fuse in this switched line to save my radio?
Is there a steering wheel PAC module that will FOR SURE work with my Alpine and Trailblazer?

Thanks
Mike

 

1. A switched 12V wire is going to be a switched 12V wire. There isn't really any current draw by the amp on this wire, it just sees a voltage when you power on your vehicle and turns on drawing current through the 12V constant wire.

2. An inline fuse would do nothing to save your radio in this case because there's no way the switched 12V wire could damage anything, again it's just a signal, no real current.

And for your last question I don't think I can be of much help, I'm not familiar with these units.