If the spedometer is not working and the traansmision will not shift out of second it means the speed sensor is bad, unpluged or the wiring for it is damaged.
The shif6ts are controled by the ECM (computer) and if does not know the speed of the car, it will not shift.
The gear between the driveshaft and the transmission is broke you need a knew one
it usually is the gear in the transmission Could be the vehicle speed sensor.
bad linkage in shifting cable
does the speedometer effect the transmission
The most common cause of a automatic transmission jerking, when shifting, is low transmission fluid. Fill the transmission to the full mark.
The speedometer in a 1991 Nissan 240SX may not be working due to several potential issues. Common causes include a faulty speed sensor, a broken speedometer cable, or issues with the instrument cluster itself. Additionally, problems with the vehicle's transmission can also affect the speedometer's operation. Checking these components will help identify and resolve the issue.
Is the TCM working normally and throwing no codes?
gas
The transmission computer takes the output speed sensor signal and sends it to the cluster for the speedometer reading. The output speed sensor is a likely cause.The transmission computer takes the output speed sensor signal and sends it to the cluster for the speedometer reading. The output speed sensor is a likely cause.
An automatic transmission might be slow shifting from first to second because of low transmission fluid. You might also have damaged the gears in the transmission at the area between first and second.
If the speedometer and odometer are both not working, I would blame the speed sensor. If only the speedometer does not work and the odometer does work, the cluster is bad.
Delayed shifting is because the transmission fluid is not warm enough to move through the internals of the transmission. You may need a transmission service,,,,,fluid change, new filter, etc. Transmission Fluid degrades with age.