BMW Repair: BMW 840 (4.4 litre), bmw 840, question deals

Question
Hi John, i have a 1998 BMW840 with 80K miles. I only use the car at weekends. Last weekend the the speedometer / mileage / trip meter stopped working. The weather was dry and cold. The next day everything worked OK. Next month the car comes up for its annual MOT test, knowing my luck this is going to fail again, probably just before the test. I wondered if this an electronic system with a battery backed prom somewhere and the battery is failing and closing down the system. Any clues on this? Thanks

Answer
Easy part of the question deals with the battery:  No, that's not how the system is set up.

I'd  suspect either a connection between the computer controlling the instrument panel and the instrument panel iteself, or a light for these.

There are a series of lights that cause these items to show.  Easy to replace once you get the instrument panel out.

(I'm looking for a late model 840 myself......what color is yours?, and any desire to sell?)