I'm a bit hesitant to jump in here, but what 'da hell, here goes,,,
pin 9 in the harness should have a direct route back to the battery negative/ground post.
to test, do a continuity/ohms/resistance check from 9 in the harness to the battery negative. leave it ( 9 ) in the
connector.,
you may get about 1 ohms there, that's the actual resistance of the wire.
to do a better test rig up a small light bulb, 12v, or test light, and go between 9 in the harness and the positive battery post.
do not run straight wire from the positive to pin 9, that will be a direct short and something will go POP
there must be a load there, that's the light bulb/test light.
that will give you a circuit that goes from the pos terminal, thru the light, then back to neg terminal thru the harness.
it puts a small load on the wires, a volt-meter does not put any load on wires while testing.
post edited 11-28-2024 to remove mention of PCM. should have been ICM.