So I bought a 2003 white tl type s a few months ago with relatively low clicks and now I want to upgrade from the stock bose head unit. I have read things online that once you take out the factory headunit you lose the sub and amp? My tl is the non navi version. I have already bought a headunit, the mounting kit, wiring harness, backup camera and steering wheel control interface. Now I have seen things online and it seems this won't just consist of soldering/crimping the wiring harness to the headunit and plugging it in. If anyone has has experience with this TL please feel free to help me figure this out.
headunit i got is the power acoustiks pdn-626b

 

I also have a white 03 TL-S. The sub has 2 wires that work as the RCA (so to speak) to give signal to the sub. I don't remember the colors, but a simple search should show you a few posts about them. Take the sub out RCA from your head unit, splice the center wire to the (+) wire to the sub and the outer wire to the (-) wire to the sub. Make sure your blue amp turn on wire is connected. Also, hook your powered wired outputs from your new stereo up to the harness. Some earlier models used low power (RCA level) inputs to function, but your car uses the regular high powered speaker level outputs. Make sure you get a good dash kit also. Good luck.

 

Wouldn't that cause problems with sound quality? I just put a new head unit and played some tunes and it was super distorted even at a low volume. I believe this to be caused by an already amplified signal being re-amplified by the factory bose amp.
I have been trying to locate the amp to try and bypass it, but I am having no luck.

 

I believe the factory Bose amp in a 2003 TL-S is actually in the head unit for the mid/highs, and the sub amp is pass side behind rear seat. Do some searches, you will get the info you need...

 

The amp for the speakers is IN the headunit. Once you remove the headunit you remove the amplifier. If you have distorted sounds did you try adjusting bass and treble? Are you sure you have all the speaker wires connected properly? (ie positive to positive and negative to negative) if one speaker is wired out of phase it can cause that