Can anyone tell me where the coolant temp gauge sensor is that controls the gauge on the dash. I have a 1999 Cadillac Caterra with a 3.0L engine. I recently replaced the engine an I am thinking I did not plug in this sensor. I have a dark blue wire that seems to go on a spade connector which I am guessing is the gauge sensor. Any help would be appreciated. My manual says it is by the coolant pipe in the rear of the engine standing straight up but I can't seem to find it. Any help appreciated. Thanks in advance.