DSC and DBC Warning Lights Come On After Alternator and Battery Replaced

[philassuncao]

Hi!

I drive a 2004 BMW 320i. It's got about 172,000 kms, and no after-market upgrades. We have regular maintenance done on it, including a tune-up about 5000 kilometers ago.

The other day while driving all of the warning lights on the dash came on. I pulled over and turned the car off. Attempting to turn it back on, nothing happened. After being towed to our local import mechanic, he told me the alternator was bad and needed to be replaced. So, we had it replaced. 20 minutes after taking it home, it wouldn't start again, so we had it towed back to him. He ran another test said the load test showed that the battery wouldn't hold a charge anymore, and that often happens after an alternator dies (why the batter wasn't checked alongside the alternator in the first place, I have no idea). So, we replaced that too and picked it up this afternoon, just before closing time.

Alongside this, we had the power steering pump replaced. The replacement part was used. While I am pretty sure this is a separate issue, I'm offering it here in case anyone feels it may be connected. The power steering went a few weeks ago and we waited for a used replacement part (being assured that continued driving, while more strenuous, wouldn't harm the car) rather than a new one because of the cost ($160 vs $1000).

We also had the ball joint replaced on the front passenger side, as it was badly worn. Again, this may or may not be related, so I'm including it as another clue.

GETTING TO THE ISSUE

We picked up the car this evening, again right before closing time. Within 15 kms or so of driving, two yellow warning lights came on and stayed on - the dynamic stability control (dsc) and dynamic brake control (dbc) (see flickr.com/photos/awakenedwellness/8028276547/in/photostream for a photo - you'll need to copy and paste the link as I don't yet have linking privileges).

If you turn the car off and then turn it back on, the lights go off. They come back on again after 3-5 minutes of driving (regardless of speed, straight vs. turning, etc.) and stay on until the car is turned off again.

Before taking it back to the mechanic (or perhaps to a different mechanic, I'm beginning to wonder about this chain of things breaking), I'm wondering if anyone might have some advice to offer about this.

• Is it possible that the new alternator and/or battery have triggered some kind of electrical fault or blown fuse?
• Is it possible that one of the many repairs we've had done in the last few days could have created a loose wire or broken sensor or something that is giving these warning lights (possibly even though the systems are fine)?
• Is it possible that the alternator, battery, DSC and DBC all broke within a 24 hour period?

And finally, can I safely drive my car with these 2 systems being disabled or faulty?


Thanks for any help you can provide. I'm really not mechanically inclined, and when stuff like this happens I am not sure if it is really happening or if I'm being taken to the cleaners by the only import mechanic in town.

[dharmabmw]

BMW's have computers out the kazoo (and some inside for good measure). There is a very good chance that the replacement of the alternator and the subsequent requirement for a battery may have caused other issues. You will need to have a diagnostic check done to see what codes may be stored. As well, the battery needs to be registered with the car's charging computer and the alternator is part of that system.

[bmwdirtracer]

The E46 doesn't get battery registration.

What you need to do is exactly what dharma said: read the codes in all the computers with a BMW diagnostic computer.

It's possible, that before your alternator died, it was delivering excessive voltage - I have seen 18-20 volts, which is certainly enough to fry any computer.

However, I believe that the most likely cause of your current issue is that the replacement alternator is BAD. If it was anything other than a Bosch FACTORY remanufactured unit, in a black Bosch Box, or a part direct from the BMW dealer, I'd bet dimes to dollars that the replacement alternator is faulty, and that the alternator isn't charging your system.

Never, ever buy a replacement alternator or starter that's not in a black Bosch box, or a genuine BMW replacement part from the dealership.