Trouble code 15 CTS signal high voltage

Okay, there is confusion on my part. There are two male plugins to the ECM. C and D are on one plugin to the ECM (that has only alphabet marked slots on it) and 10 and 12 are on the other ECM plugin (that has only numberical marked slots). D is an empty slot with no wire feeding into it, I do find the yellow and black or dark brown on the numbered plugin in the numbered slots #3 (solid yellow) and slot #7 (solid black or dark brown). Each show no (0.00 ohms reading) resistance to the corresponding temp sensor plugin's terminals. No slot on the alphabetised plugin has a corresponding solid yellow wire, and while there are black and dark brown wires, no slot wires seem to be connected directly to temp sensor.

Would it help to add contact gel to the terminal connections?

Another question then. If I turn the ignition on and I check the voltage between ECM slots 3 and 7. What voltage should I be expecting to read? It appears that it should be 4 volts (as the trouble tree is based on either over or under 4 volts). The next step on the trouble tree is to check the ohms for each wire (which had 0.00 ohms resistance) which if I read it correctly from the trouble tree is normal (or open)? That only leaves the problem with the ECM connector. So if I check the voltage at the ECM will I risk doing damage to the ECM? And if I can then I have eliminated the ECM as the problem, the wires themselves, the plug, and I previously tested the sensor (and it ohms tested in accordance to the temp to resistance values chart). This leaves only the connection at the wiring harnesses to the ECM? Or am I misreading something?