Battery charging?

So my battery light comes on randomly...
I have an intravee and so i check the voltage and it is 13.8v at idle.
I ran fault codes and it shows intermittant alternator communication. Is this my alternator thats on its way out?

The issue is my car charges fine whenever i check it? my battery seems happy.
Anyone got any ideas? i don't want to pay lots to replace alternator if its not crap
 
Well it seems obvious to me , you have an intermittent alternator problem, which is not yet causing any real issues, so keep driving until it gets worse or change the alternator now, 13.8 volts is OK for charging voltage.
 
+1 fixit man
check connections for loose or corrosion signs and monitor situation. Cheers Baz :thumbsup:
 
well I was happy it would be alternator... however when you google there is talk about it being a coding issue?
The battery light isn't like cars of old where it came on when charging was interrupted but its more that the ecu interprets it all. Very different to cars of old. Wondered if anyone knew of weak points in the system.
The light is always on on startup and if its not on when starting never comes on so just seemed old - its on before the car starts
 
Yes, you're right, as I was writing the post there was some memory of the ECU being involved, not sure if it controls the charging or just monitors it and controls the warning light ? of course it could still be the alternator..guess you'll need to get some diagnostics equipment on it !
 
Have a look at the link below, seems that the DME does control the charging, there is a way to isolate the alternator to make sure it is charging , but your fault would have to be present at that time, with it being an intermittent fault that could be difficult... good luck :)
http://www.bimmerforums.com/forum/showthread.php?2085865-Charging-system-on-2003-Z4
 
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