TPS voltage question

I'm trying to test my TPS sensor to see if it is causing a problem I'm having but am getting mixed results. My Haynes manual tells me to insert the pos. probe into the middle wire and the neg. into the ground which they say is a black wire. My harness doesn't have a black wire but from what I've read it's wire C. Unfortunatly it doesn't look like my probes are long enough to get through the back of the plug. I pulled the plug to test it to make sure I am at least getting some voltage. Well with the pos. on the middle pin (B) and the neg. on pin C I get nothing. But with the pos. on pin A and the neg. on C I get 5.36 volts. Shouldn't I get something on B-C? And the truck is an '89 4.0 with a 5spd if it matters.
Thanks,
Brandon

The middle pin will only have voltage with the TPS connected. It feeds a variable voltage (depending on the throttle position) back to the ECU.

I don't like to back probe due to damaging wires and it's a pain.
I now have shaved a little insulation off to expose wire and tape it when finished.
Be sure to reset ECU when correct voltages are obtained by disc. battery I like to turn ignition to start then short disconnected mains together. Reconnect and go through computer re-learn procedure.

That's a great idea, thanks!

Use a couple of pins pushed thru the insulation