Speedometer and odometer not working

I have a 1993 Toyota pickup, 4x4, standard transmission, 93K miles. This truck has a speedometer sensor. I have located the sensor and want to determine if the sensor is bad or the wiring to the sensor is bad. The electrical connection to the sensor has 3 wires. Can I use a voltmeter to verify if the wiring is bad? What should I see when looking back to the speedometer cluster when I look at the 3 wires? How about looking into the sensor? Sorry I don't have the color of the 3 wires that go back to the speedometer cluster.

The odometer is not working as well as the speedometer not working. That is why I suspect I may have a wiring problem between the speedometer sensor and the console. I will be measuring resistance between the 3 wires that go from the sensor connection to the speedometer/odometer. I am not sure what to expect. I suspect I will see a resistance for the speedometer. The 3rd wire may go to a power source, I'm not sure. I was told the power sensor needs power but is not protected by a fuse. That is why I suspect a wiring problem. The speedometer went sporadic(ie bounced around for a few seconds) before it completely stopped working. Hope this helps.

Thanks