Nissan Maxima: Weird speedo on my 90GXE

My 90 GXE's speedo has been acting weird the last few months. When I start
up either in the morning or after it's been sitting awhile, the speedometer
will register speed while standing still. Either in Park or when I shift
into neutral, rev the engine, the speedo registers speed as if I'm moving.
When I put into Drive with foot on brake, it still shows that the car is
moving. The odometer also registers mileage as I can see it slowly turn!
After the car's been driven some, the speedo will sit back on 0 when I come
to a stop and behave normally. This happens everyday- it's not just an
intermittant occurence.

Any thoughts??

Chris
90 & 94 GXE's

"Chris H" <net> wrote in message
news:ccvn8m$airnews.net... 

The speedo unit is the first point for the speed sensor signal, there is
some processing done by the speedo unit (sine wave signal is squared up and
frequency divided by 8) before the signal continues on to the ECU/TCU etc,
the odometer motor is also driven off the speedo assy.. I think it would be
unlikely the speed sensor is faulty in this case, as it is a mechanical
device, sounds like you have a problem with the speedo unit itself, can't be
too much more help than this.. sorry

Greg.