Speedometer and tach problems

[Mollie]

Help! I have a 2002 L300. The needle for the speedometer
and tach are acting bizarre: Staying at 0 as I accelerate, then jumping
up to my speed, then when slowing down staying in place. Sometimes both
needles moving in unison, other times not. Is there a computer that
controls this?

 

[Robert Hancock]

The speedometer and odometer get their data off the Class 2 vehicle data
bus. It's possible that there's some kind of communications problem going
on - a scan tool would likely be needed to tell you that - but it's also
possible the instrument cluster is just busted.