Okay..thats a gauge overlay. It is a piece that is set overtop of your actual gauge cluster. (I have the same one) The wire that drops from that piece goes to another connector that should be wired into the switch (where you turn your headlights on). Has this ever worked? If so, how did it become disconnected? More than likely the connector will still be wired up somewhere. But its hard to say where the previous owner wired it.
As for the other gauges youre talking about, if its in your A-pillar (between your driver side door and windshield) those are not stock. The A/F gauge should be connected RED= switched 12v BLACK= ground PURPLE= the o2 sensor. The Voltage gauge RED= switched 12v BLACK= ground. But both are pretty much a light show as they are useless. (unless the A/F gauge is a wideband)
