Aft of the coolant temp sensor (2 pin connector) is a third sensor ( single spade connector). It isn't the gauge sender; that's closer to the front. Anyone know who this sender / sensor might be? It was disconnected when I purchased the vehicle, but since then I have found some horrible wiring problems (decay) and have rebuilt the harness. In doing so, there was one black wire with no termination found in the harness with the length to reach this switch or sensor. To I added a spade connector to the lost fellow and pluged it in. I've been fighting runability problems for a while now and thought that maybe this was not supposed to be pluged in. I disconnected the wire and things get worse -- acts like a feedback sender/ sensor to the ecm. Do any of your bricks have this and if so, what color is the wire if any?