o2 wiring harness question

[blk9450]

today while i was replacing my o2's, i took the wiring harness for the o2's out too so i could make sure there were no problems with it. well i found an extra wire that looks like it may have had a ring terminal or something on it coming out of the main harness plug. is it a ground, and does it matter?

 

[blk9450]

see link
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=2477103056&category=33557

 

[shawn13]

If I remember right it hooks to your oil senser in the side of the oil pan(drivers side)

 

[HISSIN50]

in case it helps you chase wires:
http://www.veryuseful.com/mustang/tech/engine/images/mustangEngineHarness.gif