central locking has gone berserk

[Philip Mew]

1984 BMW 533i Japan
VIN : W B A D B 8 9 0 4 0 7 9 9 9 0 9 3

Problems started about a year ago, but were of a minor inconvenience,
and I just lived with it, as the cost of repair was too high for a car this old, even with used parts.

Recently, the central locking seems to have developed a mind of it's own :
- when unlocking from the driver's door, there's an instantaneous locking, so that you must be be really quick to open the door
- sometimes when a door is open when reversing, and sometimes when in motion, there will be a single uncommanded locking
- sometimes when car is stopped but running, and a door is open, there will be continuous uncomanded lock, unlock, lock, unlock,etc. for many seconds
Nowadays I have to ensure that I never leave the keys in the ignition
if outside the car !

No big deal if I have to manually lock the 4 doors and the trunk.

Is there any option besides disconnecting the central locking controller ?
If no, where is it on this Japan market car ? ( I hope it's in the same location as as in North American spec cars, but after 4 years of ownership, I can't be sure ! )

Would the gas cap door be permanently locked or unlocked ?

[Philip Mew]

P.S.

By fluke, I discovered that when the radio lost power, it was protected by 8A fuse No. 12. It looks like this same fuse also protects the central locking, interior light, light intensity on the digital clock only display, and glove box light.

[ROYinGA]

[Philip Mew]

Unfortunately, no !

[ROYinGA]

it is located in the right side well behind the speaker on my car. I found some working modules at a Pull a Part yard. I popped the cover off of mine and it actually was a small ground strap at the bottom left corner of the PC board that had come unsoldered. Take back the side mat, take out the speaker, there are a couple of little screws, loosen them a few turns but don't remove. Slide the module up about 1/4 inch and the module should unlatch and drop down to where you can remove it and unplug it. Best to disconnect the battery first and keep it vertical until you unplug it otherwise you will mess it up. I forget some of the details. Look at the ETM on e38.org/e28 as there is a wiring diagram and maybe an install picture.