1998 740IL Lost power to the onboard monitor, radio and sunroof only

All of the other systems work fine including a/c, electric steering wheel etc. All fuses are fine front and back. Any ideas?

January 31, 2013
A service shop, (not a BMW) in my area check the car and came to the conclusion that the reason why my systems are cutting down is because my battery is not producing the 900 amp output it needs to crank the car. Therefore, the computer begins to shot down systems to allow the car to start. He said I should replace the battery and all the problems will be gone. I check the battery and the eye is black even though the car starts as normal. Any counter advice?

Ignition switch. PM me.

Should I replace the switch and key as well?

Renard

Neither.

What do you suggest as a fix? I disconnected the battery for a few minutes and connect it again. The radio and onboard monitor started working again, however the sunroof did not.

Just as BMWFF suggested. Ignition switch. You can replace or clean. You dont have to change your key. PM BMWFF as he suggest. Hes got a pretty good method for cleaning.

Thank you. I will

How do you clean the switch?

I'm lost. Why not check the health of your car's battery as originally suggested? You can unlock your OBC and do TEST 9 (if you don't have a multi-meter). If your battery's voltage is at 11.89 volts (or below)...it is at 0% state of charge...which means the original suggestion is accurate.

It doesn't cost a thing to unlock your OBC and only takes a minute or two...and once the OBC has been UNLOCKED...you can check your battery in less than 20 seconds. (see video below)

Low battery voltage can cause weird electrical gremlins...just as the original suggestion...the car will go thru a sort of "rolling brown out" shutting down non essentials to keep the car running.

Thank you for the reply. I did replace the battery and all the on the OBC and radio problems are gone except that the sunroof does not open. The fuse is fine and the sunroof was working fine before the other problems started. What do you suggest?

Thank you in advance

Originally Posted by Renard

Thank you for the reply. I did replace the battery and all the on the OBC and radio problems are gone except that the sunroof does not open. The fuse is fine and the sunroof was working fine before the other problems started. What do you suggest?

Thank you in advance

After electrical interruption ...the sunroof requires reinitialization. See the instructions from the owners manual (see far right column POWER LOSS OR MALFUNCTION: