Help Needed - Odometer & Tripometer Issues

[curlyjoe]

I would think odometer data would be written to a memory chip periodically (every second or perhaps more frequently?). So when you turn on the ignition, the stored odometer would be read from the memory chip. The reason I think this is the case is that all batteries fail so small backup battery would not be reliable enough for an odometer. The clock may be linked to the battery though. However, memory chips fail too so maybe that's the case here?