Rally dash oil pressure gauge issue.

If the guage is bad why is it moving to almost half with a 10 ohm resistor but not at all with the sender at 10 ohms? It isnt so much accuracy at this point I am trying to get the thing to move. I would think its resistnace sensitive, at this point I can pull the connector and check resistance on the gray wire, but into the PC board not so much. i am wondering what its seeing at the gray wire from the sender.