It seems there are a few 124 Spider owners that wish to rectify the omission of the CD player, and so I thought I would write a short article on the subject. I am not considering this project for myself however.
Fiat chose to omit the CD players in all 124 Spiders, in return for a deeper storage cubby, even though Mazda has decided to continue installing them in the MX-5 until MY 2019, at least in some regions like North America and Europe. Apparently, the same wiring harnesses are used, so if you’ve got a Bose package, the wiring for the CD player will be there (MY 2017 + MY 2018 only*), as evidenced by the notation “CD player prep” on your options list. I’m not familiar as to what else is included with the prep package (brackets?). If you have the Technology package in the Classica model as I do (no Bose), I’m not sure if the CD wiring is included or not.
If you do make the decision to install a Mazda CD player, you would need to order the appropriate interior cubby compartment trim, to finish it off correctly. The parts department should be able to inform you whether the necessary mounting brackets are provided (or required) with the CD player unit. And of course, you would need to remove the ⊕ positive battery harness prior to the installation (standard procedure for any electrical work) so that the CMU will recognize the addition of the CD player when the battery is reconnected.
⇓ I doubt that you would have to tear down the vehicle quite this far in order to install the CD player. but the photo gives you a good idea of the brackets involved. If so desired, there is a possibility that a small subwoofer could be installed in the passenger-side void as well. Click on the photo to enlarge further.
- When the CMU receives the operation signal/detects the switch operation, it sends (1) the control signal to the TAU. In addition, the control signal is sent (1) to the CD player.
- When the CD player receives the control signal, it sends (2) music information such as the album name and artist name of the inserted CD to the CMU, and it sends (2) the audio signal to the TAU.
- The CMU converts the received music information signal to a LVDS signal and sends (3) it to the center display. The TAU sends (3) the received audio signal to the speakers.
- The center display indicates (4) the music information signal based on the LVDS signal. In addition, the speakers output (4) the audio based on the received audio signal.
* [UPDATED 12/5/2020]