Odometer dancing LEDs?
 

My odometer was gradually going blank more and more of the time, so I eventually took it out and replaced the capacitors on the board. Now it works, but every time I turn it on, it does a little LED diagnostic and lights up all the LEDs for all the digits in a little circle pattern for a few seconds before showing the mileage and trip computer. Is this normal? What causes it to do this?

Well, I cleaned off the contacts on the back of the board and the weird dancing diagnostic behavior went away, so I guess it's some sort of secret test mode.

you will get the led's to do a self test if you first turn the key to the ignition position while holding down the trip odometer reset button at the same time. So it could be possible that the contacts for the trip odometer button was sticking???