For Speed sensor 2 located in the transmission/front differential:
1: remove connector from speed sensor
2: remove speed sensor
3: Reconnect the connector to the speed sensor
4: Place a multimeter set on DC voltage between pins 1 and 2 on the connector. (middle and left)
5: turn the little metal "T" that comes out of the sensor.
It should jump between 5V and 0V 4 times per full revolution of the "t".
If it shows a continuous 5V, you may have the uhhhh... wrong pin 1, switch the outer probe to the "other left side".
(And leave the middle as is.)
They usually "open" on a fault by design, so if it's broken, you will not see a voltage on the output. It will remain at zero volts as you rotate the "t" if it's inoperative.
Let's hope it's inoperative. If it works, then it may be your "drive and driven speedo gear set"., and that will turn out an expensive repair.
The good news is, the sensor is usually the culprit, and not the gear set.