You have to replace the instrument cluster in most cases.
replace the sensor which is usually in the rear diffrential or the transmission case
You might have to take the car to a certified speedometer repair shop
You can fix the speedometer in your 1994 Oldsmobile 98 by replacing the speedometer cable. If changing the speedometer cable does not fix your speedometer you will need to replace the entire speedometer.
Speedometer cables can dry out over time. Remove the cable from the back of the speedometer, and lube the cable with graphite. This should fix the issue.
Check your fuses before anything else. Easiest and cheapest fix.
How to fix heater in Buick there is cool air ,fan is work .but no warm air
Unhook both sides of battery and wait 1 minute, this will reset reset the computer to default.
how to fix speedometer for Toyota mr2
I need to fix the odometer and speedometer in a 97 ford explorer
Send to a speedometer repair shop or replace speedometer head
The light is on because there is a fault in the system. It would be best to have the professionals take a look at it.
If the speedometer is not working it probably needs a new speedometer cable. If the speedometer is actually broken either take it to as speedometer repair shop or replace it.