Need to figure out what's wrong with them, first.
The best way is to buy a book on your model and see if you can do it. Then! Ask again on this sight for help when you feel confident that you know what your doing to repair the speedometer.
Unless you can find a rebuilder on the web then you can have the dealership send it off for repair. You could also look for one at a junk yard.
Unless you can find a rebuilder on the web then you can have the dealership send it off for repair. You could also look for one at a junk yard.
Broken cable?
from a breaker's yard, authorized dealer or possibly even Ebay.
It is an electric speedo so it can be the speed sensor or in the speedo itself.
its a fuse
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If both speedometer and odometer do not work, usually the pulse signal are missing. E.g. the wiring coming from the rear differential where the sensor is located, can be deteriorated (broken or shorted). If speedometer only is inoperative, it is easiest to change the whole speedometer. To repair it, you need to be able to work on electronics, disassemble the speedometer unit, access the printed circuit board, and usually replace the leaking electrolytic capacitors on that board, as well as clean the circuit board of the electrolyte. Some other components may be broken also.
The 1991 > 1994 Chevy Lumina Speedometer, Odometer and maybe the RPM gauge gets a signal from the ECM computer. This ECM signal is feed to a module in the instrument panel, which feeds the three items above. If all three are not working replace the instrument panel or the module (which is inside the panel), but swap the odometer to keep your mileage correct for the vehicle. Note: The ECM gets its signal from a VSS on the Transmission and the ECM feed three areas in the car: Speed Control, Speedometer and one other (?). If the speed control works, the problem is not the VSS or the ECM. The problem is in the Instrument Panel.
To give you an answer we need to know more specifically what the problem you are trying to repair is.
getting speedometer to work on a 91 chev it is most likely the vehicle speed sensor on transaxle pass. side, about 40 dollars at part store