you can try some other tests... first "looking one way" then the other. By this, I mean disconnect from the tcm, on the cable connector at the pins you identified, do a resistance measurement across the pins... this will check the path thru the cabling to and including the PCM... depending on what's inside the pcm circuit. In general, you aren't necessarily looking for an "absolute" value but to see if you see resistances of some form. You can do the same test, reversing the leads as this may change the reading IF there is some active component in the pcm (ie. diode or such). Note these should be carried out without powering. You can do the same tests in the "opposite direction" (ie. at the PCM end) and compare the results. They might show differences that may be obvious... ie. very high or very low readings in a certain directly. The test can also be done on one pin only to a body / good ground. All these kind of try to check an "unknown circuit design" / "black box". Further since you have another module you can do further comparing.
NOTE: because the circuits at the end are somewhat unknown, things like capacitors and such may cause the reading to slowly change as they charge / discharge... no a problem, but note / observe what happens.
Perhaps some other tests when powered can be done BUT the pins are close / difficult to isolate so you should be careful to avoid shorting and causing more problems.... probably leaving these types of tests as a last resort.
A quick search of the net shows this.... not sure if is applicable but some aspects may apply to help understand what your measurements are seeing.
PIC4957: HIGH SPEED LAN Diagnostics / Remembering Ohms Law - (Sep 2, 2008) Subject: HIGH SPEED LAN Diagnostics/Remembering Ohms Law Models: 2004-2009 All Cars The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI. Condition/Concern: ...
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