One method to checking if the speedometer sensor in the vehicle is working is to simply remove it from the housing and attaching the main wires to a volt meter and set it to AC settings. This will allow the technician, or vehicle owner, to determine if the sensor is functional by the frequency emitted, at which point it can be determined if the device is functioning properly or not.
If the speedometer and the odometer are not working, I would suspect the VSS (vehicle speed sensor). If only the speedometer is not working I would suspect the instrument cluster has problems.
If the speedometer and odometer both quit I would blame the speed sensor. If only the speedometer quit I would blame the instrument cluster.
It doesn't have one. It uses a speed sensor and drives the speedometer electrically. If your speedometer isn't working, it could be the sensor or it could be broken solder points on the instrument cluster circuit board.
The speedometer is part of the instrument cluster, and is fused with the other instruments.
You need to determine if it's the speedometer itself that's faulty, or the vehicle speed sensor. If the speedometer is faulty, you'll need to replace the instrument cluster.
We had the same problem, and our 1998 F150 needed a new instrument cluster.
It is inside he instrument cluster. attached to the speedometer.
Nothing
If both the speedometer and odometer are not working I would suspect the VSS (Vehicle Speed Sensor) is at fault. If the speedometer doesn't work and the odometer does, I would suspect the instrument cluster is at fault.
Stepper motor for speedometer has a broken gear in it, causing unpredictable operation. If the odometer is still working, then the speed sensor is OK. Instrument cluster needs repair.
If the speedometer is not working but the odometer is, I would suspect the dash cluster is at fault. If both speedometer and odometer are not working I would suspect the speed sensor on the transmission is at fault.
Could be the speed sensor or another common problem with neons is broken solder points on the instrument cluster circuit board. To test it, see if your cruise control can keep you at speed. If so, it's the instrument cluster. If not could be the speed sensor. If you don't have cruise, then you may have to inspect the cluster for broken solder points.