where does the extra wire on my co2 wire connector go

Tought to tell from picture without being able to see number of pins. If it is a single conductor wire on the connector then it is probably for the rear knock sensor. There is an extension harness off the knock sensor as it fits in a tight area behind rear of block and trans housing. So cable for knock sensor is probably laying on trans housing or steering rack, it should mount clip into hole on bottom corner of power steering resevoir. If it is a 2 conductor wire it could be for alternator, if 3 conductor wire it could be MAP sensor.