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.
General Information: Antenna
- Vehicles without radio do not have any antenna equipment.
- Vehicles with R100 radio have only one rear window antenna
- Vehicles with RCD 300 or RCD 500 radio have one rear window antenna with two trap circuits. The diversity function is carried out directly in the radio unit.
- If the vehicle is equipped with a radio unit and also telephone equipment or auxiliary heating remote control, antenna system has rear window antenna with 2 trap circuits and diversity as well as a roof antenna.
- Vehicles with RNS 300 radio navigation system have the roof antenna without diversity and a roof antenna.
- Vehicles with RNS 2 navigation system always have a rear window antenna with 2 trap circuits and diversity and a roof antenna, regardless of additional equipment.
The antenna system with diversity function serves to improve and optimize the reception quality in the vehicle.
To do this, the antenna signal entering the radio unit is checked and the result is sent back via an additional antenna connection. The information about the test result applies to antenna selection control module. Function is switched to another antenna when antenna signal is determined to be weak (diversity). This procedure is not audible to the customer.
Antenna Systems from 06.05
Vehicles from 06.05 have various antenna systems. The version depends on vehicle equipment. The following are possible versions:
- Vehicles without radio have no rear window antenna and a antenna without any connections is installed on the roof.
- Vehicles with R100 radio have only a roof antenna with antenna mast.
- Vehicles with RCD 300 or RCD 500 radio have a rear window antenna with a right antenna amplifier as well as a roof antenna with antenna mast. One diversity function circuit runs via the rear window antenna, the second via the roof antenna.
- If the vehicle is equipped with a radio unit and also telephone equipment or auxiliary heating remote control, antenna system has rear window antenna with 2 trap circuits and diversity as well as a roof antenna.
- Vehicles with RNS 300 radio navigation system have a rear window antenna with a right antenna amplifier and a roof antenna.
- Vehicles with RNS 2 navigation system always have a rear window antenna with 2 trap circuits and diversity and a roof antenna, regardless of additional equipment.
Before troubleshooting or servicing, the technicians must be familiar with the function and operation of the radio system.
For additional information, refer to operating instructions.
When the battery is reconnected, check any affected system or component (radio, clock, comfort electrical connection etc.) according to the repair information and/or the operating instructions.
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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.