Speedo problem

[solarman216]

Took the wife's (new to her) TDi out today with the intention of filling it with fuel as the other day I used it and the trip meter said 320 and as the gauge read just under quarter tank, was thinking this is good, more than 300 on less than a tank, but then saw the trip was 990 and when I was doing less than 30 the thing was reading 50 plus? so pulled the dash from the year later TDi I have and sorted it, odd I thought that there was a lot of oil in the casing, realise now that there must be a breather problem with the box and oil is slowly being pumped up the drive cable, but that does not explain the odometer malfunction but I guess this is a human error, reset button accidentally pressed but not right home, could find no other fault with it, however I did notice something else, a magnetic reed switch????? on checking it is normally closed but opens once per cable revolution, so it must be feeding speed info to the ECU, maybe Ray can tell us what is going on? Rick