Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2021 Mazda 3 BaseFACTORY OEM SERVICE PROCEDURE
AM/FM radio
- When the CMU receives the operation signal/detects the switch operation, it sends (1) the control signal to the remote tuner (RT).
- When the remote tuner (RT) receives the control signal, it switches (2) the tuner inside the remote tuner (RT) to radio mode and initiates reception of radio broadcasts.
- The remote tuner (RT) detects the radio broadcast selected by the user using the tuner in the remote tuner (RT) based on the electrical signal received (3) from the center roof antenna. The audio signal of the detected radio broadcast is sent (3) to the speakers. In addition, the frequency of the detected radio broadcast is sent to the CMU.
- The CMU converts the radio broadcast received from the remote tuner (RT) to a GMSL signal and sends (4) the GMSL signal to the center display.
- The speakers output (5) the audio based on the audio signal sent from the remote tuner (RT). In addition, the center display indicates (5) radio information based on the GMSL signal.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.