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.
Antenna system with Diversity function
The "Symphony" / from MY04, "Concert" /from MY05 and "Chorus" systems have an antenna system with diversity function. This improves and optimizes reception quality.
In addition to the roof antenna and rear window antenna with amplifier, an antenna in the rear or side with an amplifier is also used.
Individual antennas with amplifier are controlled via the Antenna Selection Control Module J515 (Diversity box).
The signal going via the antenna wire (HF) from Antenna Selection Control Module J515 into Radio R is checked and the results is output back to the Antenna Selection Control Module J515 via an additional antenna connection (IF).
If the antenna signal is too weak, the Antenna Selection Control Module J515 switches to another antenna (diversity function).
This switching process is neither seen nor heard.
The procedure is the same as "switching diversity".
With "phase diversity" , the Radio R has two internal tuners with one input each (AM/FM1, FM2).
If the signal received is interrupted, both signals are digitalized and separated in the tuners in the Radio R so that the disrupted signals are blocked out as much as possible.
If the reception signal is not disrupted, the Radio R constantly compares which antenna (amplifier) has the strongest reception. This is then transferred
In this case, the second tuner checks the frequency band in the background for better reception frequencies for the selected station. If a better signal is found, this tuner switches to reception and the other to the background.
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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.