Chrysler Repair: 2000 dodge neon Radio Wiring PCI bus Wire

Question
QUESTION: Roland,
More on my daughters 2000 Neon...someone cut the radio harness wires out of the car to do a hack install on an aftermarket radio...I am repairing it to factory connectors to do it right, but there is one extra wire I am having trouble with.  I got a factory harness from the junkyard out of another 2000 neon and what I have is the C1 and C2 connectors (7 pin gray and 7 pin black).  The extra wire I am having trouble with is a Violet/Yellow wire that is referred to as a PCI bus wire on the wiring diagram from autozone.com.  It says it goes to the C3 connector.  This is the only wire that is referred to for the C3 connector for the radio wiring.  The wiring diagram shows it goes back the the data connector.  What does the C3 connector it refers to look like?  Is it critical that I hook this wire up at all for the radio to work?  What exactly does this wire do?
Thanks,
Frank

ANSWER: let me check the wiring and get back shortly, Frank.

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QUESTION: CORRECTION - the C1 Connector is Black and the C2 connector is gray - also the ground is separate from the 7 pin plugs - it looks like this factory radio must have had a ground tab on it for the ground wire to plug into as it is a separate 1/4 inch spade terminal on the factory harness on this car

Answer
That black wire has a spade to attach it to a screw on the radio chassis and it should be itself grounded at the other end on the lower center edge of the dash with another ground wire which is black/light green. If the car has speed control the wire would have gone first to a splice that attached it to a ground wire from the steering column's clockspring and then to that ground point.