2002 Bose amp replacement help

Hey hive mind, I�m replacing the double din unit in my 2002 C4S coupe with a single DIN, deleting the lower console and installing an amp. I�d like to sense check what I�m doing before I do something semi permanent with the car! I�m planning on using as much of the original wiring as possible, removing the Bose main and sub amps and replacing them with an Alpine unit in the frunk. I�ve found this helpful diagram which seems to tie up to my car wiring and also I�ve found the CAI article on how to wire the rear and door subs in series. My question is about interpreting this picture correctly. If I read this right, the sub input is in the K12A01 plug. I�ll need to take these to the new amp sub input. Then, as per the CAI article, wire the doors and rear sub in series to the amp sub out. Does that sound correct? The ISO stereo outputs come to the amp on pins marked FL, FR, RL and RR on the P2 plug in the diagram below. Is this correct? If so, I�ll run them through a LOC then RCA cables to the amp inputs. I can then run the relevant speaker wires to the amp. This just leaves me with power, ground and the control wires. Power I�ll take directly from the battery as it�s a probably going to draw more power than the Bose amp. I�ll find a ground point near the amp. This just leaves the control wire. There are a few PLUS SWITCHED connections to use. Can I simply use one of these as the signal? I�ll check they are actually 12v only when the ignition is on but this fellas the best way. Hopefully my research is good and this makes sense. Let me know with a yes or a no. i

If I read this right, the sub input is in the K12A01 plug. I�ll need to take these to the new amp sub input. Then, as per the CAI article, wire the doors and rear sub in series to the amp sub out. Does that sound correct? If you remove the main bose amp you will lose the line level sub input into the K12A01 amplifier plug. The main bose amp takes the standard 4 channel line level inputs from the headunit, does some DSP/crossover work and outputs a sub line level that is sent to the dedicated sub amplifier (additional amp) If you are just looking to wire your new 5 channel amp output to the rear subs using the stock wiring, use terminal A7, A8,A11,A12 (they both go to the rear subs, not the doors) The ISO stereo outputs come to the amp on pins marked FL, FR, RL and RR on the P2 plug in the diagram below. Is this correct? If so, I�ll run them through a LOC then RCA cables to the amp inputs. I can then run the relevant speaker wires to the amp. FL,FR,RL and RR are line level inputs on the P2 plug. They are NOT speaker level signals. No need for a line output converter. Wire it directly to the RCAs. You can even get factory connectors to do this, search around for late 90s early 2000s GM bose adapter harnesses. They'll have matching plugs. Another oddity with the 2002 bose setup, the rear speakers are not discrete left and right output. It's summed into one set of wires at the amp. This just leaves me with power, ground and the control wires. Power I�ll take directly from the battery as it�s a probably going to draw more power than the Bose amp. I�ll find a ground point near the amp. This just leaves the control wire. There are a few PLUS SWITCHED connections to use. Can I simply use one of these as the signal? I�ll check they are actually 12v only when the ignition is on but this fellas the best way. I'd strongly recommend using the stock grounding points. These cars are susceptible to ground loops. Yes the plus switched is good for the remote turn on wire you need for the amp. It's not switched with ignition but with the head unit. Stick with the stock wiring as much as possible, you'll end up with the lowest chance of interference/EMC issues. It's all twisted pair and has had quite a bit of engineering put into it. Depending on what amp you are using, if you need a 5 channel line level input, the best way to get this would be to use something like this, and tie the sub channel to the front main. https://www.audiocontrol.com/car-aud...s/matrix-plus/ My current setup is using the factory bose amp and that matrix plus to bypass the DSP the bose amp does on the sub channel. I've got a Kicker Key 500.1 driving some Peerless drivers in the factory cabinet.

I took a ton of photos but can't seem to find them. The PO had a MOST box wired into the stock Bose amp. I replaced my Bose amp with an Alpine 5 channel amp, removed the MOST box, and used the stock speakers (for now) and stock wiring. Hope this helps some...

Wow, thank you so much for the detailed answer! I think I was on the right track with most of it but the sub information was new to me..I'll experiment with the amp and see if it will do the DSP to generate the sub out from the 4 channel input, in which case I'm good, or if I'll have to work something else out

A quick update, I’m almost finished and so much of this has been useful. I’ve got a couple of questions though. First, as suggested the rear speakers are a single twisted pair from the original amp. I’m going to run this off of a single channel on my 5 channel amp, mainly as it’s the only option. I can up the gain for the rears to compensate if needed. Any issues with this approach? Second I’ve tried running the rear sub as a single channel, wiring the 2 speakers in series. I know this is contrary to the CAI article, which might explain my problems. The amp doesn’t seem to like this, it spits its toys out and refuses to play if I up the gain or volume above minimum. I’ve not run it in series with the doors yet, I’m going to try that and see what happens. Any thoughts before I do? Other notes, I’ve not found the right iso adapter. The one I got wasnt correct and I’ve had to jump through a few extra hoops as a result like finding the right control wires and giving up with the line level outputs and instead running a pair of rca cables. However, the “right” adapter was 4x the price and even then might not have worked. I could have repinned the adapter but the channels shared a common ground which I know isn’t correct so it wasn’t going to work. Aside from that, all is going well.

I answered my own question by giving it a go. Rear speakers into 1 amp output channel works, I can adjust the gain to ensure the sound stage is balanced properly. The doors and rear sub are now wired in series and after playing with the low pass filter, gain and noise, it sounds soooooooo much better. All that remains is tidying up all the cables and mounting the amp properly.