How do you fix speedometer on 89 Toyota Camry?

check the cable that runs from the gearbox to the dash. (the connection IN the dash looks like a green receptical for a light bulb, its HARD to miss)

make sure that it turns properly and that, when in its correct position, turns the small brass coloured part inside the speedo mechanism (the end of the cable should be a square-ish prong that is should insert into a hole in the extreme rear of the speedometer mechanism).

if the unit doesnt work (if the cable is fine and the mechanism bares no apparent defects) see a wrecking yard about buying a new one

(that's what i did when i found it didnt measure above 45km/h)

all the trip meters and odometer all run off the same cable (as the speedometer), so if they are still operating (except the speedo) then i would suppose the cable is in good order and the problem lies somewhere else.

the taco is digital. so don't worry about that.

that's about as far as my knowledge goes on this. maybe it helps, maybe I've told you what you've already observed.