The speedometer sensor relates back to or through the ECM and to the cluster in digital or analog out put.
If the speedometer and odometer doesn't work I would suspect the VSS (Vehicle Speed Sensor) is faulty.If the speedometer doesn't work but the odometer does, I would suspect the gauge cluster is at fault.
Check VSS(vehicle speed sensor)on tranny,the most common problem of speedometer errs,providing your vehicle is equipped with a speedometer cable.Also,VSS,will cause erratic speedometer reads. - Big Daddy
Vehicle Speed Sensor
A fuse is not directly used with the speedometer itself, but it is part of the vehicle's electrical system that powers the speedometer. If there is an electrical issue, such as a blown fuse, it can cause the speedometer to malfunction or not work at all. Therefore, while a fuse may not be specifically designated for the speedometer, it plays a crucial role in ensuring its proper operation as part of the vehicle's dashboard systems.
Most common would be speedometer cable has broken Remove speedometer head and move vehicle to see if cable moves- if not probably broken - if it does probably problem with speedometer head
If both the speedometer and the odometer do not work I would suspect the VSS (Vehicle Speed Sensor) located on the tail shaft of the transmission is at fault. If only the speedometer doesn't work it's probably a problem with the dash cluster.
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
The speedometer.
Probably a bad vehicle speed sensor.
A faulty vss (vehicle speed sensor).
check the Vehicle Speed Sensor on the transmission or possibly the rear axle.
The VSS vehicle speed sensor on top of the transmission is faulty.