Resurrecting a CDR-23, wiring help

I'm in the process of bringing a newly acquired 04' GT3 back to 100% stock and am currently working on resurrecting the stereo head unit. At some point someone put a crappy kenwood unit in and it appears they tapped off part of the original harness, see photos. I purchased a working CDR-23 but not having any luck getting it to work with the available harness connectors that were still intact. Can anyone let me know which ports on the CDR-23 need a harness (perhaps all?) and where I can source the correct harnesses to connect back into the tapped wiring from the previous owner's kenwood hack job? Additionally, the CDR23 seems to be just barely too large to fit into the 1 din OEM opening. Is the metal insert shown in the photos aftermarket (part of the kenwood system) that needs to be removed prior to CDR-23 installation? Thanks in advance.

Be thankful. The previous owner that installed the "crappy" Kenwood actually used a proper aftermarket wire harness to interconnect the last radio to the car. Remove it along with eh connected female ISO terminal dock. It appears that your 996 was ordered from the factory with the base audio system meaning that it did NOT use MOST transfer bus to send signals to an frunk amplifier. You need to confirm if you have factory amplifier. Again, because you have the brown ISO plug, it's my opinion that your GT3 definitely had a base model radio which meant the headunit powered the speakers. The black ISO A plug (socket) handles the basic functions such as constant and switched 12V to the headunit. The brown ISO B plug (socket) is for speaker level output. Use the attached guide for reference. You probably DON'T have door speakers do you?

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This is far from a "hack job". I've seen systems that had all the original plugs cut off and wires regrounded and positive 12V terminals tapped into other system components making it a potential fire hazzard. At least the previous owner used a proper wire harness. That is because you need to remove the Kenwood metal mounting adapter frame that connects to the Porsche black plastic center console frame.

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Thanks for the detailed help, super helpful. Correct - I do not have door speakers and based on my quick research online and photo below (my car), I don't have a factory amp. I purchased the pictured CDR23 second hand, not original to this GT3. Did all CDR23's come with a built in amp as you described that could power the speakers? Theoretically, it should just be a plug & play with the connectors I have, correct? Given my setup, any reason it shouldnt work by simply connecting the ISO A & B plugs to the CDR23?

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I was right! Yay! . Without the door speakers, that means you do NOT have a frunk amplifier which is not uncommon for GT3 buyers who want the lightest car possible. I'm not 100% on this, but when Porsche moved to MOST transfer bus in MY2003 they worked with Becker/Harman to make the headunits programmable or "matched" to the car's audio options. Therefore, if the car had a base level audio system, the CDR-23 would be programmed from the factory to output SPEAKER LEVEL from the brown ISO socket. However, the majority of CDR-23 units came from the factory ready for MOST fiber optics. There is no harm trying the unit with your car, but more than likely it will power up but NOT output audio. You would need to find another CDR-23 that came from a car with the base audio setup OR, you could always purchase a CDR-210 or CDR-220 and call it a day. Those units are great and analog only. They will also be a direct match to the ISO plugs in your car. See above. Try it. No harm, no foul. Report back your findings. Again, I predict it will power up but not produce sound.

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You were spot on, once again! Really appreciate all the help. The black plug powers the unit up and brown plug unfortunately does nothing. Just powers up but produces no sound. Do you know if these CDR23's can be modified to act as an amp to power the speakers? Worst case I'll move to one of these other CDR models you suggested, but rather go with what originally came with the car if at all possible.

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Again, not 100% on this, but I believe the CDR-23 units come from Becker as switchable to either MOST optic output or speaker-level output (brown IOS socket) which was originally configured by Becker, but I believe can be reconfigured with a PIWIS. Can you confirm you had a CDR-23 on the option list? That would be how I'd approach it with the Porsche or an independent shop that has a PIWIS and knowledgeable of OE radio configurations. I do know that a lot of people would upgrade from a base radio like the CDR-23 and move to a PCM unit when purchasing a car from the dealership. This was a up-service that many of the Porsche dealerships would handle... for a charge of course. The PCM radio would then be configured for the car. Remember, some had BOSE, others had the "Hi-Fi systems" with frunk amplifier from HAES or Nokia, and then lastly like yours... that had neither and required the headunit to power the speakers. IMHO, the easiest route to have modern functionality and retain a OEM factory look would be to install a Porsche PCCM single DIN classic. They come ready to output via the speaker level outputs. ISO connections from your plug directly into the PCCM. The only thing you have to run is the GPS antenna which mounts under the alarm beacon on the dash and the USB backout box. While it says it's made for 911 cars up to the 993, it will work with the 996 especially base radio systems like yours. You can see in the attached photo of the back of the Porsche classic single DIN radio, you have the two main ISO plugs (left of the blue fuse), one is for the BLACK ISO and the other for the BROWN ISO. This unit will give you standard radio, Bluetooth streaming audio, and GPS navigation. Plus it will power your phone. https://www.suncoastparts.com/product/SKUCLASSIC.html As mentioned before, the most inexpensive option would be to purchase a nice used CDR-220, but make sure you get the 4-digit security code.

Turns out I actually bought my CDR23 from Becker Auto Sound ( https://www.beckerautosound.com/ ) and they've been very helpful and willing to swap my CDR 23 for one that's wired to power the speakers. I'm in that process right now and will report back but and hopeful!

Full circle on this as I'm sure others will run into the same issue - I was able to swap out my CDR23 to a unit that was programmed to act as an amp instead of relying on a non existent external amp that most 996's came with. Plugged it in and works great!