BMW Repair: BMW 540i 2000 (E39) - minor electrical nuisance, bmw 540i, fuse boxes

Question
This is what's happening and I believe they are all related to the same source. I just do not know what to look for.

1. When the engine stops, the OBC clock time stops.
2. when I lock or unlock the car, the signal lights do not flash. However, audible sound is heard. Before, the lights would flash once when locking and flash twice when unlocking.
3. On occasion, if the trunk is chacken as a result of heavy groceries, or droping the spare tire or something, it resets, the travel tach (0.0), time (-:-pm), mileage cons1, cons2 (-/l/km). Oddly enough, the radio stations are retained and only the year in the date (00/00/2007).

I believe the wiring in the fuse box (located in the trunk) might have to do something with it. If so what wire do I check. Btw, all the visible fuses seem fine.

Can you help me? Your time and effort is much appreciated.

Regards,

Martin  

Answer
Interesting.  I wouldn't assume all are caused by the same thing, though it's possible.

First thing I'd recommend is checking the battery voltage.  This can be done through the dash by unlocking the system and checking via the dash readout.  If you don't know how to unlock this, check the ROADFLY.COM message boards, or email me back again.).  The voltage being low, due to a dying battery cell, can throw all kinds of electronics off.

1.  Does the clock stop, then restart when you start the car again?  Or does it reset?

2. Locks.  I thought that by 2000 the e39's had the option of having the lights and/or sound when locking.  Check your manual, it might be that you accidentally changed an option you have.

3.  Interesting, and probably key.  Since one of the fuse boxes is back there (another key one in front, and a few others hidden around!), it could be something loose here.  Do the lights (trunk light?) go off when this occurs?  Being that the battery is back there too, it could be a corroded battery connection, (or a corroded ground from the battery), and that could be the cause of all the problems.  Or it could be an individual connection, but that should be visible.

After reviewing these, I'd focus on the "dropping" things in the trunk.  Try "shocking" the rear area with something that won't cause damage.  Try banging on the floor of the trunk with a baseball bat or 2X4, and seeing if you can create the problem.  Once you can create it, resolving it becomes a lot easier!

Let me know what you find