Check Control Display Flashing Garbage

[jaypitsby]

Ladies & Gentlemen:

On occasion upon starting my 1990 525i, the Check Control Display starts flashing nothing but garbage or random characters. It goes on for a few starts and stops of the engine and then seems to disappear. The display then goes back to its normal functions.

Is this some kind of recalibration it is performing or is it a sign of impending failure? It has occured about three times over the year that I have owned the vehicle.

Thanks in advance.

[mjm]

There is a service bulletin about this, late now, but I can look it up for you later, something to do with the aux coolant pump not having a protective diode and causing interference. The fix is to replace the coolant pump with one after a certain date.
I also have a 1990 525i, and did see this 2 or 3 tiimes about a year ago, but nothing since. BUT.....then last summer I had a worse problem -- the check control display portion of the LCD backlight stayed on all the time, even with the ignition off. Finally, after living with it for months, I pulled the two 1.5W backlight bulbs. I don't think it's related to your problem, but if anyone has ever heard of this happening and knows the cause or fix, PLEASE let me know. Thanks
1990 525i

[gordon]

Before trying anything "big"... loosen the cluster and reach in behind and make sure the three plugs are seated.... I had garbage show up (really weird stuff) and it was a loose plug (the big orange one I think).

[Warren N.CA]

Remove and replace each plug. This will clean oxidation off the contacts, and it should be OK for a while. To make the fix last longer, apply Stabilant 22. http://www.stabilant.com

Before trying anything "big"... loosen the cluster and reach in behind and make sure the three plugs are seated.... I had garbage show up (really weird stuff) and it was a loose plug (the big orange one I think).

[MJM]

That service bulletin was #62 0190 3007 from August 1990, apparently only a problem with E34s (and E32s) with the redesigned cluster. The description was "After switching the ignition ON, flashing and illegible displays may alternately appear in the LCD Display Module."
I only saw this two, maybe three times, so didn't bother with it.
Maybe I should try the Stabilant for my own problem with the backlight staying on, good suggestion, have already tried unplugging and reseating a couple of times.