Sat Nav & Radio command problem

[thebassman]

Hi Guys need some tech. help, my W203 C280 SE 56 plate has had an intermittent fault on the Command Unit, sometimes it comes on and works normally (radio/ sat nav, etc ) and other times the screen is blank with no audio. The last couple of times it fires up for a couple of seconds and then goes blank. I have disconnected the battery for 30 minutes as is suggested but this has not worked. This morning I got this message on the command screen, Battery Voltage Too Low Command Switching Off. The battery on the car is only a year old and everything else is working fine. Thanks in advance. Jeff.

 

[AMGeed]

The battery may be only a year old, but that isn't to say the voltage hasn't dropped and why you re getting that message.

I'd check the voltage with the engine off and if its lower than 12.6v, put the battery on charge.
This chart shows acceptable battery voltages.

 

[thebassman]

Thanks, don't have a voltmeter so will buy one tomorrow and check that.

 

[Larkone]

Possibly corrosion on a fuse/relay contacts at that age of car, especially if nothing else is affected. Had similar (2008) with my screen washers running slow, only 10.5 volts at the pump. Pulled all of the fuses and relays and re-seated them and now works fine - never found which fuse or relay was the culprit though. A meter will help.

 

[thebassman]

Have removed and checked the fuse and will remove and re seat the relays tomorrow. Haven't been able to get out for my voltmeter so hopefully tomorrow as well.
Thanks.

 

[thebassman]

Have finally managed some time on the car today, voltage on battery was 12.2v, put it on charge and its now 12.8v, taken all fuses and relays out and put them back but still getting nothing on the command screen apart from the Mercedes Benz logo. Have also used my iCarsoft V2.0 code reader which shows no code faults I can purchase a second hand one for a couple of hundred quid but reluctant to do so if the problem could be elsewhere. Anyone know if these are prone to failure ?
Any help appreciated
Thanks, Jeff.