[djamroz]

Hey guys,
First of all I am new to this forum and my e90 330i 6spd manual .
Forgive me if this was posted before, i have searched high and low with no luck.
My sound system will not work properly. I will turn the car on and one of three things will happen :get either static from the rears with fronts barely working, rears working ok with no subs or fronts, or no sound at all. My settings on the HU dont stay saved, with the exception of eq settings. Bass, treble, fader, etc reset by themselves.

So I tried almost everything and found one thing that helps. Every time i disconnect the battery then re-connect and turn the car on, everything works great. My settings on the HU(Bass, treble,etc.) magically pop up and the system sounds great.
That said, I'm almost convinced its the HU but come here for some additional info/opinions on what it can be.

Thanks!!

[Technic]

New battery perhaps?

[ctuna]

Do you have a voltmeter to read the voltage?

[djamroz]

The battery is relatively new. 4-5 months(ish). Should i look into it?
And unfortunately I dont have a voltmeter. Ill try and grab one from a buddy.

[HomeBrew]

I had some similar issues with the i-drive in general.

Turned out to be a dirty / loose ground connection on the battery.

[ctuna]

Did you have your battery registered?(tells the car it has a new battery and adjusts the
charging rate accordingly its a programming step)
It may not be charging at the correct rate if you didn't.

[djamroz]

Ill clean the terminals on the battery and see what happens. But im not sure if it was registered. The person i bought the car from gave me the receipt for the battery as part of the service record. How can i tell if its registered?

[ctuna]

Chances are it wasn't registered . BMW started putting on what they call the Intelligent Battery Charging System in the 3 series with the introduction of the
E9x model . For the guy that's used to changing the battery himself this is a pinta. You can go to and independent BMW shop or to the dealer to get it done.
Only they would be able to tell if its registered.
The third option is by a Bavarian Technique Scan tool which is capable of registering the battery.

I doubt the terminals are the problem and when you go to look at whats on top of the battery you will find a mess of wires . I wouldn't bother with cleaning the terminals if it looks good.

http://www.e90post.com/forums/showthread.php?t=392533

[djamroz]

Okay thanks. Ill get it checked out. But I still dont understand how the battery would cause static or no sound. Hope its as simple as that.

Im going to add that I can sit in the car, just put the key in, radio will work, take it out and put it back in and nothing and/or static. Can that really mean the battery?

(Key: I have comfort access but currently dont have a legit transponder key. Only emergency key. Dont know if that could make a difference)

[ctuna]

If the battery check eye on top of the battery is green its probably not
the battery . If the battery reads about 12.5 volts its probably not the battery.
The battery would have to be pretty low but strange things could happen it it was.

What happened to the two CA fobs that were suppose to come with the car?
Also have you replaced the battery in your comfort access fob . You can get them for
about 3 bucks at a drug store.

Could be your L7 amp is going bad there had been a rash of that on here lately.

[djamroz]

Now that you mention it, the eye is not green. Ill check that out. Battery is around 5 months old so that could mean battery wasnt coded as stated by a few others or just a bad battery?

I bought the car private party without the CA fobs. All i received was the emergency key...My Bmw dealer is trying to help me out with it

But if its the amp, why would my settings on my HU change to default by themselves. (Example: Set bass, treble to +2 each, take out key, wait five minutes, turn on and HU is set to default 0 but time and date stay correct)

[Bavarian Tech]

If ur using the "plastic" emerercy key, the car isnt going to remember your setting aka for bass, treble, memory seat etc

[ctuna]

Not registering means that it will be undercharged I think.
Also if you leave it setting around a lot and don't go out on any long
trips to charge it you might consider using a battery tender .
The only way this would explain static is if the radio was tunes to
a non existent station.

My battery is in the black now it reads 12 volts on my meter .
I have CA and I'm not having any trouble but it looks like I need
to replace the battery soon.
No way should the battery be in the black at 6 months.
even with abuse.
You could try putting a slow charge on the battery and see if
it comes back to green.

[djamroz]

You might be right because he did tell me that he very rarely drove the car after putting the new battery in. And it's been sitting for me for about a week. However I did put a slow charge on it for about an hour and didn't seem to change anything. Eye is still black and even with car charging I still encounter the same problems.

And about the static, it is there no matter what you do. Whether on cd, radio, or aux, it stays constant only in rear speakers. Volume of the static does not change when adjusting vole on hu.

[ctuna]

To see if you can isolate it.
Could be blown speakers or amplifier channels.
Do the test also play with the balance to see if its just one side.

Does your charger tell you the state of charge?

[djamroz]

Could the speakers be blown? Like I previously stated, one of three things occur. Fronts don't work, static from rears or no sound. If I disconnect battery for a sec then reconnect, the system sounds great! But only till I pull the key out. Then it goes back to one of the three errors. That's what's throwing me off.

[djamroz]

If speaker or amp was blown, it would be constant would it not? Idk anymore. If I don't resolve it soon, might be time for a trip to the stealership?

[bmw325i]

Get a multimeter and check the voltage of the battery when the car is off it should be slightly over 12 (around 12.4 volts) if that's good I would just go to the dealer and let them figure it out.