Stereo PAC OS-2BOSE Question

Red955i

Active Member
Hi...Ok next mission. the 2008 Trailblazer LT 4.2 4WD I have has the UB0 Radio, UQA speaker option (If that means anything to you) It has a speaker in each door plus two small ones on the dash. There are no steering wheel controls. The previous owner had installed a 2Din Pioneer FH-X720BT head unit.



Everything thing appears to work. I can balance left to right and fade front to back. However, the right front (passenger side) dash speaker sounds lower that the drivers side, and the passenger front door sounds lower as well.

So..I pulled it apart. The head unit is wired to a PAC OS-2BOSE box with an separate relay and a separate chime box

I then went and looked up the PAC unit and I only found instructions relating to a 2003 Trailblazer. I dont know if my 2008 is the same??

In the 2003 instructions they show TWO different ways to wire it. OPTION 1 is for the Premium Bose Amp, OPTION 2 is for the Bose amp. I have no idea at the difference is, whether 2008 is the same etc.



Option 1 - does NOT use the rear speaker leads from the head unit and clearly states you lose the ability to use the FADER

Option 2 - Does use the rear speaker leads from the head unit but they bypass the PAC unit and connect through a resistor kit.

I have nothing bypassing the PAC unit and I have no speaker wires from the head unit unused
The speakers are all color coded (white, white w/blk) green, green w/blk, etc and they are all hooked to the corresponding pair on the PAC)

Therefore if I was wiring this without instruction all would look correct
It I was reading the 2003 truck instructions I would say it was not wired as it should be as the rears shouldn't be used (but maybe a 2008 is different?)

How would I go about tracking down what is causing the problem on this two speakers?

I can wire the head unit out of car and see if volume on all 4 speakers the same to eliminate the head unit
then where do I go?

As usual thanks
Bob

P.S. To those that helped with my engine replacement many thanks. If it wasn't for your help, and the physical help of a Guyanese mechanic from the shop who came to my driveway to do it (they are great people)...it would have did me in, but it runs great!!
 

Mooseman

Moderator
I doubt very much you have a Bose radio and amp as these normally come with the Steering wheel controls. If you look carefully in the dash speaker grills, it's probably just a piece of cardboard filling the hole. So this would mean you have the wrong interface for this vehicle.
 
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Red955i

Active Member
I doubt very much you have a Bose radio and amp as these normally come with the Steering wheel controls. If you look carefully in the dash speaker grills, it's probably just a piece of cardboard filling the hole. So this would mean you have the wrong interface for this vehicle.
There are speakers in those grills
 

Mooseman

Moderator
You're right. UQA means the Bose option. Very unusual without the steering controls unless that's a 1LT thing.

Check on PAC's website for which interface they recommend for your 08. IIRC, 02-03 were analog Bose and after were digital. It is possible that this interface won't work right with the newer trucks.
 

Reprise

Lifetime VIP Supporter
Agreed. By '08, there weren't two separate Bose amps any longer. You can find pics online of both; and if you're looking for the amp, it should be behind the passenger side rear panel (the long one behind the rear door) We also have the audio diagrams here, if you haven't looked at them, yet.
 

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