The 10V to ground tells me the plug needs to be double checked - make sure the (Ground for signal) return to the ECM is the same as the ECM's own ground.
Does the tester have continuity tone? IT helps to use that feature to determine if the shield/ground wire and ECM grounds are at the same potential.
Then trace back from the sensor - to the correct pin the Crank (CKP) sensor is supposed to be at at the ECM and check for continuity that way.
This sounds like an issue I had with knock sensors - once disconnected, they don't always return to having good connection and conductivity returning back to like they had before the connector got separated - I call it connector memory. That it worked when it was originally put together and survived all this time until it was unclipped and now it can't resat to make the same connections. The age of the unit compromised it.
IF the wires are that old, (2009) it may need some TLC to restore the like new conduction they need to sense the crank signal.
IT also might need to have that wire and it's shield replaced due to age. So do an ohmic check across those terminals as well as it's reference to ground (engine case and chassis to engine case - ground to make sure the shield wire is not eroded thru and shorting out the sense wire from all that handling. I mean, once the CKP is installed backprobe the leads to make sure the sensor is not compromised to ground and is causing this short itself
