Rear speakers were not included in the MX-5 NB/NBFL until 2004. Adding the wiring the way Mazda did is easy.
The first generations of the MX-5 had speakers in the seat headrests—or at least space for them. From the introduction of the NB in 1998 through the 2003 model year NBFL, there were no speakers other than those in the doors. That changed during the final model years of the NBFL—specifically, 2004 and 2005. From that point on, Mazda installed speakers behind the seats. In some special editions, a design bracket with a soundboard was used, while other models featured a wind deflector with speakers. All of these versions have wiring running from the radio to the center of the raised section behind the seats.
What many people don’t know is that there is space in the existing connectors to add the wiring for the rear speakers. Only the last connector is missing—that is, the connector that connects to the speakers in the wind deflector or in the soundboard.
The wiring starts at the connector that fits the original Mazda radio. Mazda used this connector in many models, including the MX-5 from 1999 to 2012. Space is reserved in that connector for 4 wires that carry the signals to the rear speakers. The colors of these wires may vary by model and model year. The colors shown on this page were used in a 2004/2005 NBFL.
Starting with the radio connector, the first section of the wiring harness is assembled. This first section becomes part of the dashboard wiring. It connects the radio connector to the large connector that links the dashboard to the car’s wiring. The section inside the dashboard uses 4 Yazaki type 7116-1471 terminals in the radio connector and 4 Yazaki type 7114-4021 terminals in the large dashboard connector. The cable length according to the official route is approximately 140 cm, but a shorter route is also possible. The layout of the connectors, along with their corresponding colors, is shown in the images above and below.
The second section of the wiring harness runs from the dashboard to the rear shelf. Both ends of this section have the same type of connector. In this case, we need female terminals of the Yazaki type 7116-4021. The length of the wires for this section is 275 cm if you follow the original route from under the dashboard, through the firewall, the side panel, and the door sill next to the driver, to the connector under the rear shelf.
The third and final section of the wiring harness runs from the large connector under the rear shelf to the passenger side, where it then goes back over the top of the rear shelf to the center of the shelf. For this section, the wires are approximately 185 cm long. Four wires with Yazaki type 7114-402 terminals connect to the large connector. For the connector for the windshield baffle with speakers or the design bracket with the soundboard, we use the Yazaki 7183-6153 connector. Once again, the connector layout with the corresponding colors is shown above.
To be able to use the connector, a cutout must be made in the carpet of the rear shelf. In the video below, starting at 8m45s, you can also see where that cutout should be made.
