the plastic gear in the cluster that drives the odometer and the tripmeter is probly broken ..
check your fuses
The odometer has failed.
If the speedometer and odometer both quit I would blame the speed sensor. If only the speedometer quit I would blame the instrument cluster.
i have a 1990 Isuzu trooper as well and the speedometer and odometer also quit working, they both come off of a mechanical cable that is attached to the drive train. that cable breaks, and you lose both speed and odometer indications. they are extremely difficult to find, so if you do, write me back...
Our odometer/tripmeter also just stopped working at 220,000 miles. This is an integral part of the speedometer assembly, and cannot be repaired. The entire speedometer must be replaced.
Speed sensor While yes the speed sensor can cause the odometer to quit working the speedometer will quit at the same time. If you have the electronic cluster (the orange bar with the white behind it) there is a motor that runs the odometer and that can stop working. That cluster is designed to where you can replace just that unit, although I don't know where you'll be able to find a decent working one. -answered by Sye
Check your fuse it happen to me
most likely the electricity going to them
the little gear that turns the numbers is broke and the only way to fix is replace the whole speedometer.
If you open the odometer, there are two small plastic gears. One is connected to the speedometer, the other to the odometer. The speedometer gear drives the odometer gear. In all likelihood, one of these gears is missing a few teeth. I have the same problem with my Ramcharger, same year.
i just changed the speed sensor on my 91 and it took care of that same problem.
it usually is the gear in the transmission Could be the vehicle speed sensor.