I replaced the stock "premium" head unit in my 2007 with a Pioneer flat screen unit with navigation, etc. I had to use two adapters, one so the car's computer still thought the stock unit was installed so the amp and everything else would work. The second adapter was to allow use of steering wheel controls, On-Star and such so the area behind the head unit in really packed but the stock amp, speakers, etc all work as before and sound great.

I have no idea what the part numbers are for the adapters but the stereo shop in Imperial Beach CA knew which ones were needed and I have trusted them for my automotive stereo gear for about 10 years now and no issues.

 

Yeah, that sounds about right oldracer, these Trucklets are buggers to retrofit audio gear to unless you use an "A'Dapter Kit" as Johnny Cash says in "One Piece at a Time".

Or you just yank every dang thing and start from scratch, and to the O.P., every danged "Hardcore Audio" guy I think of has moved on or isn't replying to my PM's.

Sorry man, I'll keep plowing through threads and reaching out to folks.

 

you can definitely keep your sub, it may not be plug and play meaning audio input wires to amp may have to be cut and RCA plugs soldered in, then you run an RCA wire from new head unit to the sub amp, I went the opposite way and added the factory sub to my car, what i will tell you is that the factory amp sucks, you can keep the sub speaker,others will tell you speaker sucks too but I got it to sound very good with an aftermarket amp.

heres my advice,remove the factory amp, either buy a 5 channel aftermarket amp and
use it to power the 4 speakers and sub(best solution), or buy a single channel amp to power the sub, then use the amps in the new head unit to power the 4 main speakers.
any decent car audio shop can do this standing on their head. unless you need head banging bass dont let them talk you into an aftermarket sub you dont need that takes up cargo space.you will be surprised how much better the system will sound not using factory amp, even if you keep the factory speakers

 

If I have to do this, then I'll just do what you suggested below.



I actually have the amp I pulled out of my old car. It's a cheap two channel that I used to run bridged. I think it would do the trick for the sub (it's only 100W).



Thanks, all!

 

check your impedance of the sub and the 2 channel amp you have, the HHR premium system uses 2 ohm speakers and I'm pretty sure the sub is a 2 ohm as well, most aftermarket 2 channel amps will not be able to handle a 2 ohm load in bridged mode, you may have to install a 4 ohm sub to use it

 

also, I wouldn't recommend using those factory speaker connected directly to the new head unit, I think the 2 ohm load would be too much for the HUs internal amp, definitely keep the factory amp to power those factory speakers, zapshd had the best advice to look into a 5 channel amp and bypass the factory amp altogether

 

Remember that the factory sub is has 2 2 ohm coils so you can run them in series and have a 4 ohm load, but any good sub amp is good for 2 ohms anyway

 

Thank you everyone for your input!

I took the plunge and ordered the adapter. I had to connect the "amp signal wire" from the adapter's pigtail to the 12VDC accessory line to get the amp to turn on (even with the GM LAN bus getting the command to turn on). My a'dapter kit included a relay, so I used that because I didn't know the amperage that the amp would pull from that wire. I just used the constant 12V line (87), the accessory line (86), the ground (85), and the amp signal line (30).
I currently don't have a stereo in place, but I used a 3.5mm to RCA cable, some RCA Y adapters, and RCA couplers to hook up my phone for now. It actually sounds better than the stock HU did IMO (but then, my phone has a 32 bit DAC... :) ).

Side note, the original HU had markings that seemed to say that the stock speakers are 4 ohm, not 2 ohm. *shrug*

New hole in the dash:


Adapter and chime box temporary placement with RCA Y adapters:


ACC relay (red is the ACC line, Yellow is constant 12V, Blue is the "amp signal", and Black is GND):

 

Keep plugging away!! Pun intended!! Nice work so far!