looses clock settings and shows either left or rear brake lamps out?

What DID the dealer do?

The dealer said to perform battery leak test and replace it for $800.00
Thank you.

And did that battery replacement fix the issue?

Honestly, I did not feel comfortable to spend so much money so far.

I feel that, thanks. Is the problem gone?

No, but usually my wife drives about 40-45 miles daily. last weekend we went for the trip totalling app. 300 miles each way and so far the clock is OK, but I still get messages about rear brake lights malfunction and as I said I replaced bulbs and harnesses and both lights come on every single time when I apply the brakes.
Sorry for the description being so long.
Thank you.

You might need to consider replacement of the rear light assemblies due to these false faults

Thanks, I will check it out as well and keep you posted

OK

Hello good people. I'm replying to a very old post, but am curious about the content. I have just purchased an '08 X5 that is doing the EXACT same things as TRIKTRAK12's BMW. I have already replaced the battery and the alternator and still the clock is clearing, the rear light warning is on, and now I'm getting an "engine malfunction" warning. Hoping someone out there, anyone, found resolve. :)

Hello,

There can be two things going on. First the bulbs can change in resistance which can cause wearing, here is a video on a similar car with the same issues to show you how to fix it:

https://youtu.be/JJeRxRi7Lpo

Also, there is an alarm module that goes out as well again this car has a similar system that had the problem. I have included the location of the module for your car in the images below.

https://youtu.be/3S0Ns3O3ULA

The keep alive battery should be in the junction box on the right side of the dash. But before you go to the trouble, we should make sure by doing a CAN scan. You can get a CAN scanner (Controller Area Network) from Amazon from about $32.00.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Amazon CAN scanner link:

https://amzn.to/3sX8MCX

Check out the images (below). Let us know what happens and please upload pictures or videos of the problem.

Thanks for all the great info, Ken! Much appreciated. I'll be back, hopefully with good news!

Please let us know what you find. We are interested to see what it is.