2000 BMW 540i Battery Drain/CD changer

[huckendr]

My 2000 540i with 80,000 mile has has two episodes of morning dead battery during the last two months. The battery is a three year old BMW factory battery
an tests OK when charged.

After I completed an extensive trouble shooting session on the electrical system to flush out the problem to no avail I suspect the BMW dealer installed CD changer in the trunk. The changer was installed when I purchase the BMW new in April 2000 and no problems until now. The unit is hot wired and not switched and will activate when connecting the battery thus going through a clunking and clicking sounds for about 10 seconds that appears to be a normal process. I have read in other posted items of this same issue of the changer waking up and draining the battery. There is no obvious pattern to this is issue.

I have all the tools and meters needed including a clamp on DC amp meter to trouble shoot the problem. If I could just get it to produce the problem while I am present I could figure it out. About all I can do is pull fuse 56 for a few months and if it doesn't reappear I might have narrowed it down to the changer. Problem is no radio if I pull this fuse.

Should the dealer not hot wired it directly from fuse 56 prewiring in trunk? Is there a switched option for wiring this changer so when the car is put to bed the changer is deenergized?
Am I on the right track or could this problem be caused by some other spuratic issue?

Help!

Roger H

 

[Doughnut]

Welcome to the board!
I'm not familiar with your bimmer, but i do know that most cd changers are wired directly to the battery so you dont have to have the acc or ignition "on" to eject and change cd's.
My car's 12 stack is like this too.
If you wanted to check to see if it is your changer that is draining it, you could posibly put a tempory switch in the cabin that is inline with the power to the changer. switch it off when not using the changer. it would be more convenient than pulling the fuse out.

My thinking - good luck.

 

[bimmerZ5]

i hope everything you're talking about is BMW factory component? If not, there are too many variables.

BMW uses a protocol called I-BUS for the CD changers. There are two plugs that connects to the factory Cd changer and they provide the I-BUS wire and power. If you unplug the power connector, there will be no power to the CD changer. This might be easier than unplugging the fuse.

In I-BUS, the headunit(HU) is king. The HU will send out a broadcast about every 16-18 seconds saying "hello! who's out there?" ... accessories like the CD changer (CDC) will respond and say "hi! i'm a CD changer, and I'm here" .. this is how the headunit automatically detects a CD changer when you connect it. If for some reason, the HU doesn't shutoff properly, it will continue to boardcast that signal causing the CDC to respond and hence not goto sleep. Or, if the CDC received that signal, but got stuck somehow and continues to reply to the HU, it will not go into sleep mode. When not in sleep mode, these accessories can drain more power. It should only awaken when the car is turned on and the HU broadcasts or you hit the eject button.

There are a lot of components in BMWs these days that don't power off completely, but instead go into sleep mode. Your ZKE (body control unit) is another example.

I think the short way of investigating this further is to unplug power to your CDC which should power it off. See if your battery still drains. I believe the power connector is the one with less pins.

 

[huckendr]

2000 BMW Battery Drain/CD Changer

Bimmer Z5

I shall pull the plug on the CDC and enjoy the radio on demand.

Thank You!

I unpugged and pulled the CDC from the trunk today and will operated for about 3 months to prove or disprove the problem. I've had the fuse out for a week now with no problems. The CDC is a BMW dealer installed unit.

It's great to have the radio back!

 

[huckendr]

UPDATE!!! The CDC remains out of the trunk and I have not experienced any unexpected battery drain since it's removal. I'm now 100% sure the CDC is sporadically schizophrenic and can't find itself thus cycling until it drains it's energy source. I wish I could send out the CDC for treatment does anyone know of a good therapist (repair facility).

 

[supra88]

HI I have seen this problem before and it was the cd changer made by pioneer
i never seen this problem with any other changer ,bmw,alpine
only with the pioneers when they go bad changer stay on all night ,or sometimes they just wake up and kill your battery