I have: 1993 22re 4wd pickup Automatic transmission

My issue: The Overdrive light is flashing and giving me code 61 (No.2 Speed sensor). The speedometer works fine and shifting seems to be working correctly.

I tried:

1. Check continuity between SP2 and body ground: I'm connecting to the wires/plug that connect to the ECU (SP2 and E1). Getting nothing.
2. Read wire voltage: Reading voltage of wires that connect to the sensor (with key turned) shows ~11V.
3. Check speed sensor: Unplug sensor cable and connect ohmmeter to the sensor (two outside prongs). Reads 1mΩ. I jacked up a back wheel, spin the wheel, still reads 1mΩ.
4. Unplug speed sensor: Speedometer doesn't work and it doesn't shift at all.

What else can I try before buying a new sensor? The previous owner said he recently replaced this exact sensor for this same reason.