help!! Electrical issue - buzzing behind driver's backrest

[Gary Knox]

I drove my 97 840Ci about 1500 miles in the last 3 days, attending The Vintage in Asheville NC.

Today on the way home, there was a LOUD buzzing in the cabin when I came to a stop in a line of traffic where the interstate hwy was blocked. VERY loud, but as the traffic cleared and I started to pull away, it diminished, and was not audible above road traffic noises. I stopped at an exit, and as the egine rpm dropped, the buzzing noise became louder again. It DID NOT stop when I turned the engine off, but may even have gotten louder. Trying to locate the source, I found it was coming from the driver's backrest, as it was REALLY loud when I put my ear to the plastic piece behind the backrest. I had no choice but to continue driving, and am now about 250 miles from home at a hotel. I also noticed that when the car was parked and engine running, it was very loud at idle, and nearly disappeared by 2K rpm.

Being very concerned about a malfunctioning electrical circuit and both the heat it might generate and the possibility of running the batteries down, I disconnected the battery grounds at the combined jump post and locked the car. Now, I find the key will not unlock the trunk!!! Guess I'll need a jump from AAA tomorrow morning to get power to the system so I can open the trunk to re-attach the ground connections.

Any comments about help, what it is, what fuse would eliminate it so I can continue home tomorrow would be INCREDIBLY appreciated!!

THANKS in advance for any and all help. Information about which fuses or relays to pull to temporarily stop this would be appreciate, of course.

Also, for the first 3 or 4 times I stopped, the car could be locked/unlocked with the transmitter from the key. The last two times I stopped it, that method would not lock the car. I could only lock it with the key in the door lock.

Gary Knox

[Gary Knox]

Thanks CDO, I don't think that button has been touched, but it's worth trying to find out tomorrow morning, once I get electrical power on again.

Gary

[vet73]

You can get the trunk lid opened with the key. If I remember correctly, you enter the key into the trunk lock under the lid (over the car's tag) and turn it a quarter turn and press it upwards to physically unlock. You could search threads to find posts with more detailed info but the procedure is a fairly simple sequence to open without power being 'on'.

[PabloRock]

Thanks CDO, I don't think that button has been touched, but it's worth trying to find out tomorrow morning, once I get electrical power on again.
Gary

That's because you have too many cars! And as vet said, you can unlock the trunk with the key. It's kind of pain to figure out (it is some sort of twist and push), and takes me a couple of forum searches and attempts to get it when it happens to me. Since my batteries are disconnected for the moment while I do some work, I put a sock there so it doesn't lock on me.

[Gary Knox]

Paul,

Yep, I'd put a sock or towel there as well - IF I'd been home. Since I had a bunch of stuff, including a valuable part for the e9 in the trunk, I didn't want it 'available' overnight!!

OK bottom line is THIS old computer on wheels is just like your old home PC or laptop. When it gets cantankerous, just reboot it. AAA came over to the hotel this morning at 8:10 and put 12 V to the charging posts in the engine bay, I started the car, the trunk opened as soon as I pulled on the latch bar. Re-connected the two ground straps, tightened the nut, and the AAA guy removed his 'jump'. Turned the car off, re-started perfectly. So, I locked it via the remote, went in to check out of the hotel. Came back, unlocked it remotely, opened the trunk, replaced the stuff I'd taken into the hotel, left and filled it up with gas and reset radio code. Drove 250 miles home - everything associated with the car was just like the TV commercial for the company that cleans up after floods or fires: "just like nothing ever happened".

So I now know that 12 hours without any 12V power will correct THIS (and probably many other) problems. I still do not know for sure what the buzzing was, but I'll investigate is some time soon. IF it comes back, first thing I'll do is park, remove the ground straps, sit and look at the scenery for 10 minutes, then re-connect and see if that short time re-sets everything.

THANK YOU ALL for all your suggestions. I've posted this solution for any who experience this issue in the future.

Gary

PS Out of nearly 600 cars at The Vintage, there was ONS other e31. Guess what color and year!!! Yep - '97 in Calypsorot. Two differences between our cars: license plates were GA and PA, the other interior was Parchment, and it has nearly 2X the miles on it's chassis. Had a nice chat with the owner. There must have been three hundred 2002's.
Accomplished my objectives: Meet and chat with at least a dozen other e9 owners (one was from Huntington Beach CA, one from New Orleans, and one from Maine!), Drive the 'Tail of the Dragon' across the mountain from TN to NC and drive at least 50 miles on the Blue Ridge Parkway. So, even with the disruption and the constant rain on the way home, it was a good trip. The 840 did very well on the Tail of the Dragon, I actually caught up to motorcyclists about 5-6 times going up the hills. They were very courteous and pulled over at the first opportunity, allowing me to pass. Must have seen 150 motorcycles in the ~20 miles.