Antenna: Testing and Inspection

Antenna Diagnosis

Antenna diversity is a system that select the antenna with the best reception from the up to 4 antennas in the vehicle. This signal is amplified in the diversity and passed on to tuner. The following briefly describes the tests that can be run in the antenna diversity test module.

DC measurement
The DC measurement detects whether the diversity is correctly connected to the tuner. In the test module, the corresponding diagnostic trouble code memory entries are also evaluated.

Self-diagnosis of antenna diversity
The antenna self-diagnosis checks the diversity function and antenna connection. However, these results are not always meaningful. In this case, it is necessary to examine the field strength of the receiveable stations.

Service mode
In the Service mode of the radio, there is the possibility to display the quality and field strength of the radio station currently being picked up (not M-ASK and CCC). The displayed values lie between 0 and 15.
- 15 corresponds to very good reception
- 0 corresponds to very poor reception

Proceed as follows to call up the Service mode:
- Terminal 30g ON
- Switch off the radio
- Switch on the radio again
- Within 8 s for a duration of 8 s, press the button for manual station-search function
- The radio switches into the Service mode

Assessment of the reception quality in the test module
If the result of the diversity self-diagnosis is OK, the field strength of the currently received station can be displayed in the test module. If one antenna has a noticeably weaker reception than the other antennas, the vehicle must be turned by 90 degree and the measurement repeated. If there is still a violation of the tolerance range, at least one FM aerial is defective. The defective FM antenna must be checked.

Checking AM antenna / testing Rad_on signal
In the diagnosis, the AM amplifier is inactive and therefore delivers level values with the AM amplifier switched off during an AM scan. To evaluate the AM antenna with the active amplifier, the test is concluded by switching the switching voltage from the diagnostic mode into FM1 / AM mode. With the amplifier switched on, the level values must be significantly higher than those with the amplifier switched off. If this is not the case, the Radio_on cable must be checked.