535i speedometer problem

[cwcullen@xxxxxxxx]

I have an 85 535i with 98k miles which has the following speedometer
problem: 
   The speedometer reads fine.
   The odometer and trip odometer read exactly one half the miles driven.
I've checked it against mile markers and it is extremely close to 1/2.
   I've had the car for only about 3k miles and have no idea when this
problem started.

Two other factors: 1) I checked the SI batteries and they have the
correct voltage-3 volts as printed on the batteries. I know, according to
everything in writing they are supposed to be 1.2 volt NiCads. Well these
are 3 volt lithium. They have 90-04 printed on them and they look like
they came with the board, so I would assume the board was changed in mid
or late 1990, and a new "improved" type was used. 2) The gas gauge
fluctuates when the tank gets below 1/3. 
I don't think either of those factors has anything to do with the
odometer problem, but thought I would mention anyway. 

Anyone have any idea what the problem is and what is the solution? Any
help appreciated.
Thanks in advance.

Wes Cullen
85  535i
BMWCCA 138721

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