The digital odometer reads "error" and the engine hrs.screen reset itself to zero. Can I reset the computer by diconnecting the battery?

Did you try disconnect batery for 5min.

Could be a problem with the engine computer, or the speed sensor in the transmission.
Is the check engine light on ?

You'll need to reset the Electronics Control Computer otherwise called the PCM/ECC/ or ECM. You can do this by unhooking the battery cable for about 15 minutes. If this does not reset it, you may have to do it for up to a day then try hooking the cables up again. See if this works.

Your question peaked my curiosity, so I did some digging.

Looks like the problem is in the body control module. It could be the prom or the computer itself, or a connection. The odometer is not getting the data from the BCM.
You could try a GM dealer if you can find one that still works on 1980s models.

Have the dealer do a speedometer accuracy test. They have a special tool that can electronically read the speed and then compare it to the readout of the odometer.

{: ) You may wish to record the latest odometer and engine hours reading while still visible, just for future purposes. The problem is an internal circuit failure on the Instrument Panel Cluster (IPC). Sooner or later the two message screens on your IPC will totally go blank and goodbye, so be prepared.
A replacement IPC will be that of later models, it will be programmed to your vehicle, and the trip odometer (total mileage) will be reset to zero.

On most vehicles if you leave the battery disconnected for 3 hrs the computer will reset. This is enough time for the power back up in the computer to go dead and reset itself. I know it sounds stupid, but it works. Should make check engine light turn off

1. With your car OFF, place your key in the ignition and turn to "On". Do not start the car.
2. Find the odometer button and press until it reads the total odometer setting, (not the Trip A or Trip B setting).
3. Turn the key to OFF.
4. Place your finger back on the odometer button, press and hold. At the same time, turn the key back to "On".
5. Hold the odometer button in until the MAINT REQD light goes out...should take about 8-10 seconds.

page 77 of the 2004 Lexus rx330 handbook...
(you will find the answer you are looking for in resetting your maintenance light.)
with the odometer reading visible, (not trip A or trip B..) turn off engine.

While keeping Odo/trip button depressed, turn ignition back on (not starting the engine) You will see dashes (instead of numbers) on your odometer disappearing one at a time. it will be replaced by 0's (zeros).. Release the Odo/trip button and your original mileage will come up....
And your done..... until the next oil change.

Thank you for using fixya and good luck

On my 02 ford pu, if you have the digital odometer, I hold the odometer/reset button down while starting engine, it goes thru test and gives error codes. Disconnecting negative battery cable for a minute, then reconnecting, will turn off the light if there are no issues.

I have had simlar issues. The first thing to try is to diconnect the positive lead from teh battery. Be careful as there are some issuesd surrounding OEM batteries in the 02. after about 30 secs reconnect the cable. This will "reset" your system and if it is just a glitch, the problem should be gone. If this does not fix the problem it is most likely your intrument cluster, however it can also be the BCM (Body Control Module). Have a dealer check it out for you. Before you buy a replacment part from the dealer chaeck out the prices at newgmparts.com or Rock Auto, both saved me 50% or more when I needed to have these items replaced.