MX-5 BOSE / Pioneer Radio Steering Wheel Adapter

Retain Steering Wheel Control The adapter is a “steering wheel interface”: it allows the buttons on the steering wheel (e.g., volume, track change) to continue working after installing an aftermarket radio.
Other Vehicle Signals In addition to steering wheel control, the adapter also provides other signals: speed pulse, reverse signal, and parking brake signal. 
It also retains the OEM AUX input of the Bose system – useful if the factory radio had an AUX connection. 
Compatibility According to the installation manual, it is suitable for Mazda MX-5 NC (model years approx. 2005–2015 with Bose). 
Configurable Settings The adapter has DIP switches (small switches on the housing) that allow configuration for different vehicle setups. The manual includes tables showing which DIP switch setting fits which MX-5 exactly.
Why do you need this adapter? If you replace the original Bose radio with an aftermarket unit, you often lose the steering wheel button functions without an adapter. The adapter ensures these are retained.
Because the Bose amplifier in the MX-5 NC is part of the sound system, the wiring is different (not as simple as with basic radios). The adapter helps to correctly translate and pass through the signals.
Some of these adapters also forward important vehicle information (speed, reverse gear, etc.), which may be required by certain aftermarket radios (e.g., for display functions, camera switching, etc.).

What should you consider during installation?
Disconnect the battery: Before connecting the adapter, remove the negative terminal of the battery for safety.
Find the correct connector: The adapter has a 24-pin Mazda OEM connector that must be connected to the original plug in the vehicle.
Set DIP switches correctly: Depending on the vehicle setup (which Bose system, which aftermarket radio), the DIP switches must be configured correctly so that all functions are recognized.
Cable routing & securing: The “flying wires” (e.g., speed pulse line) must be routed cleanly to avoid interference or damage.
Test functionality: After installation, check steering wheel buttons, radio, reverse gear signal, parking brake, etc.

Possible Limitations or Issues
With some radios, not all steering wheel buttons may work exactly as before – depending on compatibility with the interface.
Incorrect DIP switch settings can cause certain signals not to be recognized properly.
If the adapter is not grounded correctly or the ground wire is not properly connected, interference may occur.
Caution! this active adapter only applies to conversion from the OEM BOSE radiosystem to a pioneer radio of your choice!

Fits:
MK2.5 2000 - 2005 all models with OEM BOSE radio system
MK3 2005 - 2008 all models with OEM BOSE radio system
MK3.5 2008 - 2015 all models with OEM BOSE radio system