Audio 50: Direct-entry of FM frequency stopped working
Thread Starter
MBWorld Fanatic!
Joined: Dec 2003
Posts: 1,586
Likes: 1
From: Sacramento
'08 AM Vantage V8 - '03 E500
Audio 50: Direct-entry of FM frequency stopped working
This isn’t the most important “issue”, and my car is under warranty until September, but I’m puzzled about whether I have a hardware or a software issue here. Our audio unit is the Audio 50 with small display and cassette player (whoop!).
I just noticed that direct entry of FM frequencies doesn’t work any more. Direct entry of an FM frequency (*-digit-digit-digit) causes the brief display of the first two digits entered, the decimal point, and then a four-digit number. The frequency doesn’t change and the display returns to the current frequency after two or three seconds. The four digits displayed after the decimal point have a system. The first is always “9”, the fourth is always “6”, and the middle two count down from “94” as you go up in frequency from 88. For instance, if you punch in any frequency from 88.1 to 88.9, it will display “88.9946”. If you punch in any frequency from 107.1 to 107.9 it will display “107.9756”. That’s very Mercedes, in a way – even aberrant behavior has an internal organization and logic.
The five-way control also stopped working correctly on FM. The “V/^” and “< / >” buttons on the five-way should change the frequency in 0.2 MHz and 0.6 MHz increments, but instead the “V/^” make the frequency jump to the top (107.9) and bottom (87.7) of the FM tuning range instead. The “< / >” buttons don’t do anything but make the display go blank.
Direct-entry of frequencies, and the five-way switch, still work correctly on AM radio, which we don’t listen to. Direct-entry of CD track numbers also works correctly. The “scan” and “seek” functions still work correctly on FM.
Since the last time that direct-entry worked correctly on FM we had a dead battery (headlights left on) and the car was jump-started. The dead battery didn’t cause the audio unit to lose its FM presets, though.
This problem isn’t worth a special trip to the dealer, so is there any way that I can “reboot” the audio system to see if that fixes it? Or does the fact that only FM is affected indicate that it’s a hardware problem?
I just noticed that direct entry of FM frequencies doesn’t work any more. Direct entry of an FM frequency (*-digit-digit-digit) causes the brief display of the first two digits entered, the decimal point, and then a four-digit number. The frequency doesn’t change and the display returns to the current frequency after two or three seconds. The four digits displayed after the decimal point have a system. The first is always “9”, the fourth is always “6”, and the middle two count down from “94” as you go up in frequency from 88. For instance, if you punch in any frequency from 88.1 to 88.9, it will display “88.9946”. If you punch in any frequency from 107.1 to 107.9 it will display “107.9756”. That’s very Mercedes, in a way – even aberrant behavior has an internal organization and logic.
The five-way control also stopped working correctly on FM. The “V/^” and “< / >” buttons on the five-way should change the frequency in 0.2 MHz and 0.6 MHz increments, but instead the “V/^” make the frequency jump to the top (107.9) and bottom (87.7) of the FM tuning range instead. The “< / >” buttons don’t do anything but make the display go blank.
Direct-entry of frequencies, and the five-way switch, still work correctly on AM radio, which we don’t listen to. Direct-entry of CD track numbers also works correctly. The “scan” and “seek” functions still work correctly on FM.
Since the last time that direct-entry worked correctly on FM we had a dead battery (headlights left on) and the car was jump-started. The dead battery didn’t cause the audio unit to lose its FM presets, though.
This problem isn’t worth a special trip to the dealer, so is there any way that I can “reboot” the audio system to see if that fixes it? Or does the fact that only FM is affected indicate that it’s a hardware problem?
